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}