If you want to access the accounts on MetaMask, you will need to do the following:
- Log out of MetaMask: click on the hamburger menu and select
Lock - Select
Restore from seed phrase - Paste the mnemonic that was created when you ran
truffle develop - Create a new password and confirm
Source: How can I import the accounts from truffle develop into MetaMask?
Actually, the mnemonic comes from
testrpc. That can be pasted into MetaMask and the private keys can be copied with MetaMask's Import Account feature.