Maryland makes its shaded relief lidar data available for free and in the public domain. You can added as a source for tracing in JOSM using the following WMS imagery entries. To add a county that isn't listed, head to the LiDAR server and copy the WMS link into a text editor. Then update the link with a paremeters like in these examples.
wms:https://lidar.geodata.md.gov/imap/services/AnneArundel/MD_annearundel_shadedRelief_RGB/ImageServer/WMSServer?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&SRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}
wms:https://lidar.geodata.md.gov/imap/services/BaltimoreCity/MD_baltimorecity_shadedRelief_RGB/ImageServer/WMSServer?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&SRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}
wms:https://lidar.geodata.md.gov/imap/services/Baltimore/MD_baltimore_shadedRelief_RGB/ImageServer/WMSServer?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&SRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}
wms:https://lidar.geodata.md.gov/imap/services/Carroll/MD_carroll_shadedRelief_RGB/ImageServer/WMSServer?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&SRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}
wms:https://lidar.geodata.md.gov/imap/services/Harford/MD_harford_shadedRelief_RGB/ImageServer/WMSServer?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&SRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}
wms:https://lidar.geodata.md.gov/imap/services/Howard/MD_howard_shadedRelief_RGB/ImageServer/WMSServer?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&SRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}
wms:https://lidar.geodata.md.gov/imap/services/Frederick/MD_frederick_shadedRelief_RGB/ImageServer/WMSServer?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&SRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}
wms:https://geodata.md.gov/imap/services/PlanningCadastre/MD_ParcelBoundaries/MapServer/WmsServer?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=Parcel Boundaries&STYLES=&SRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}