Some C# OxideMod examples from the documentation: http://docs.oxidemod.org/rust/#getting-started

advancedWebRequest.cs

using Oxide.Core.Libraries.Covalence;

namespace Oxide.Plugins
{
    [Info("EpicStuff", "Unknown", 1.0)]
    [Description("This example illustrates how to use a GET WebRequest")]

    class EpicStuff : CovalencePlugin
    {
        [Command("get")]
        void GetRequest(IPlayer player, string command, string[] args)
        {
            // Set a custom timeout (in milliseconds)
            var timeout = 200f;

            // Set some custom request headers (eg. for HTTP Basic Auth)
            var headers = new Dictionary<string, string> { { "header", "value" } };

            webrequest.EnqueueGet("http://www.google.com/search?q=oxide", (code, response) => GetCallback(code, response, player), this, headers, timeout);
        }

        void GetCallback(int code, string response, IPlayer player)
        {
            if (response == null || code != 200)
            {
                Puts($"Error: {code} - Couldn't get an answer from Google for {player.Name}");
                return;
            }

            Puts($"Google answered for {player.Name}: {response}");
        }
        
        [Command("post")]
        void PostRequest(IPlayer player, string command, string[] args)
        {
            // Set a timeout (in milliseconds)
            var timeout = 200f;

            // Set some custom request headers (eg. for HTTP Basic Auth)
            var headers = new Dictionary<string, string> { { "header", "value" } };

            webrequest.EnqueuePost("http://www.google.com/search?q=oxide", "param1=value1&param2=value2", (code, response) => PostCallback(code, response, player), this, headers, timeout);
        }

        void PostCallback(int code, string response, IPlayer player)
        {
            if (response == null || code != 200)
            {
                Puts($"Error: {code} - Couldn't get an answer from Google for {player.Name}");
                return;
            }
            Puts("Google answered for " + player.Name + ": " + response);
        }
    }
}

callPluginMethods.cs

namespace Oxide.Plugins
{
    [Info("SecondEpicStuff", "Unknown", 0.1)]
    [Description("Makes more epic stuff happen")]
    class SecondEpicStuff : CovalencePlugin
    {
        // First, add a reference to the plugin you are trying to call
        // The name of this field needs to be the exact name of the desired plugin
        // eg. We are referencing the example plugin above which is called 'EpicStuff'
        [PluginReference]
        Plugin EpicStuff;

        // It's a good idea to check if the plugin you're trying to call
        // has been loaded by oxide (otherwise you can't call the method)
        void OnServerInitialized()
        {
            // Note: Trying to do this check in the plugin Init() method may
            // fail, as the plugin load order may be different each time
            if (EpicStuff == null)
            {
                PrintWarning("Plugin 'EpicStuff' was not found!");
            }
        }

        void CallPlugin()
        {
            // Plugin methods return objects, so cast the API call to the type
            // you're expecting
            var getTypedReturn = (bool)EpicStuff?.Call("GetReturn");

            // Send parameters through as variables after the method name
            var takeParam = (string)EpicStuff?.Call("TakeParam", "param1", 1024);

            // Use JSON.net to process the returned object
            var returnedObject = EpicStuff?.Call("ReturnObject");

            // Call a plugin to do some work without returning anything
            EpicStuff?.Call("SendMessage");
        }
    }
}

configuration.cs

namespace Oxide.Plugins
{
    [Info("Epic Stuff", "Unknown", 1.0)]
    [Description("This example illustrates how to use a basic configuration file")]
    class EpicStuff : CovalencePlugin
    {
        protected override void LoadDefaultConfig()
        {
            PrintWarning("Creating a new configuration file");
            Config.Clear();
            Config["ShowJoinMessage"] = true;
            Config["ShowLeaveMessage"] = true;
            Config["JoinMessage"] = "Welcome to this server";
            Config["LeaveMessage"] = "Goodbye";
            SaveConfig();
        }
    }
}

CreateDataTable.cs

using System.Collections.Generic;
using Oxide.Core;

namespace Oxide.Plugins
{
    [Info("Epic Stuff", "Unknown", 1.0)]
    [Description("This example illustrates how to create a data file")]
    class EpicStuff : CovalencePlugin
    {
        class StoredData
        {
            public HashSet<PlayerInfo> Players = new HashSet<PlayerInfo>();

            public StoredData()
            {
            }
        }

        class PlayerInfo
        {
            public string UserId;
            public string Name;

            public PlayerInfo()
            {
            }

            public PlayerInfo(BasePlayer player)
            {
                UserId = player.userID.ToString();
                Name = player.displayName;
            }
        }

        StoredData storedData;

        void Loaded()
        {
            storedData = Interface.Oxide.DataFileSystem.ReadObject<StoredData>("MyDataFile");
        }
    }
}

exposePluginMethods.cs

namespace Oxide.Plugins
{
    [Info("EpicStuff", "Unknown", 0.1)]
    [Description("Makes epic stuff happen")]
    class EpicStuff : CovalencePlugin
    {
        // Plugin methods can be a simple bool that is returned
        bool GetReturn()
        {
            return true;
        }

        // Plugin methods can take parameters and return simple types
        string TakeParam(string param, int secondParam)
        {
            if (param == "first parameter") return param;
            else return "First parameter didn't match!";
        }

        // To return complex types, they should first be converted
        // into builtin types (e.g. JSON.net types like JObject, JArray, etc. or builtin
        // collections like System.Collections.Generic.Dictionary)
        JObject ReturnObject()
        {
            var myObject = new JObject();
            myObject["key"] = "value";
            myObject["array"] = new JArray();
            return myObject;
        }

        // Plugin methods don't have to return something
        void SendMessage()
        {
            Puts("You just called the 'SendMessage' method!");
        }
    }
}

StoreDataTable.cs

using System.Collections.Generic;
using Oxide.Core;

namespace Oxide.Plugins
{
    [Info("Epic Stuff", "Unknown", 1.0)]
    [Description("This example illustrates how to save to a data file")]
    class EpicStuff : CovalencePlugin
    {
        class StoredData
        {
            public HashSet<PlayerInfo> Players = new HashSet<PlayerInfo>();

            public StoredData()
            {
            }
        }

        class PlayerInfo
        {
            public string UserId;
            public string Name;

            public PlayerInfo()
            {
            }

            public PlayerInfo(IPlayer player)
            {
                UserId = player.Id;
                Name = player.Name;
            }
        }

        StoredData storedData;

        void Loaded()
        {
            storedData = Interface.Oxide.DataFileSystem.ReadObject<StoredData>("MyDataFile");
        }

        [Command("Test")]
        void Test(IPlayer player, string command, string[] args)
        {
            var info = new PlayerInfo(player);
            if (storedData.Players.Contains(info))
                PrintToChat(player, "Your data has already been added to the file");
            else
            {
                PrintToChat(player, "Saving your data to the file");
                storedData.Players.Add(info);
                Interface.Oxide.DataFileSystem.WriteObject("MyDataFile", storedData);
            }
        }
    }
}

timer.cs

namespace Oxide.Plugins
{
  class Main : CovalencePlugin
  {
    void singleTimer()
    {
      timer.Once(3f, () =>
      {
          Puts("Hello world!")
      });
    }
    
    void repeatingTimer()
    {
      timer.Repeat(5f, 0, () =>
      {
          Puts("Hello world!")
      });
    }
    
    void nextFrameTimer()
    {
      NextFrame(() =>
      {
          Puts("Hello world!");
      });
    }
  }
}

webRequests.cs

using Oxide.Core.Libraries.Covalence;

namespace Oxide.Plugins
{
    [Info("EpicStuff", "Unknown", 1.0)]
    [Description("This example illustrates how to use a GET WebRequest")]

    class EpicStuff : CovalencePlugin
    {
        [Command("get")]
        void GetRequest(IPlayer player, string command, string[] args)
        {
            webrequest.EnqueueGet("http://www.google.com/search?q=oxide", (code, response) => GetCallback(code, response, player), this);
        }

        void GetCallback(int code, string response, IPlayer player)
        {
            if (response == null || code != 200)
            {
                Puts($"Error: {code} - Couldn't get an answer from Google for {player.Name}");
                return;
            }

            Puts($"Google answered for {player.Name}: {response}");
        }
        
        [Command("post")]
        void PostRequest(IPlayer player, string command, string[] args)
        {
            webrequest.EnqueuePost("http://www.google.com/search?q=oxide", "param1=value1&param2=value2", (code, response) => PostCallback(code, response, player), this);
        }

        void PostCallback(int code, string response, IPlayer player)
        {
            if (response == null || code != 200)
            {
                Puts($"Error: {code} - Couldn't get an answer from Google for {player.Name}");
                return;
            }
            Puts("Google answered for " + player.Name + ": " + response);
        }
    }
}