Additional listening resources

You may have some luck finding some older recordings (public domain) at archive.org. You can usually download an MP3 or stream the selections. I found Mamie Smith's Crazy Blues there. Just an example; I know it's on the CD.

Another way to expand your learning experience is to create a custom radio station on Pandora. It's free. I just 'seeded' a custom radio station with Matchbox Blues by Blind Lemon Jefferson and although it won't play the song you want immediately, it will play similar stuff. The station I just created is now playing Terraplane Blues by Robert Johnson.

[Edit: Here's a tune that should be mandatory listening for students of early American music: Stealin' by the Memphis Jug Band.]