A folk song that a lot of bluesmen did — Cephus and Wiggins and Josh White spring to mind —is Careless Love. Others that seem to have been done by a lot of blues men include Frankie and Johnnie (or Frankie and Albert), Casey Jones, CC Rider, and Fishing Blues — which isn't really a blues at all. Taj Majal does a fine version of the latter. I haven't checked, but at least some of them should be in the Digitrad.

david