I don't know much about the 'songbag' heritage of America, but was given this collection of American folk music (mostly recorded during the 20's and 30's) some time ago. I think it's about time I dug it out:
Anthology of American Folk Music
I think the reviews make interesting and affecting reading:

"There is a great beauty in the voices on these recordings, many of which are almost shrill, almost off-key -- unfamiliar to our pampered contemporary ears -- but also perfectly right. There is a mystery in the odd and sometimes fragmentary lyrics, whose once important meaning is now lost.
We can still share the depth of feeling through the music itself, sometimes so strongly that your heart leaps as though you'd been kicked from inside. But, as it says in the booklet of notes, while we can share in the emotions that impelled someone to sing about The Coo Coo Bird in the first place, we'll never know why it was important to live on a mountainside in order to see Willie go by."