Semi-blues: Mississippi John Hurt & Mance Lipscomb, who was much less polished than Hurt but very interesting musicologically.

My mother got me a Brownie McGhee CD when I started taking guitar lessons. I consider him to be sort of "easy-listening" but sometimes that serves a purpose, too. At least, he's less harsh than some of the others (I still haven't learned to play like him, though. Sigh. One of these days).

Etta Baker. Very interesting country/blues style.