Stewie,

Sounds to me like you've achieved major correction; I'm not sure how I got "Big Bill " and "Casey Bill" confused. Ah, found it! According to HARD HITTING SONGS FOR HARD-HIT PEOPLE, pp. 202, "WPA Blues was sung by Big Bill Broonzy on Perfect Record (6-08-61 C-1380) from the collection of Alan Lomax. You are probably right, though. I always assumed that since Big Bill sing it, that he wrote it. Thanks for the info.
I did have a verse from Josh White (1940s):

The house I live in –
The same for black and white
My country right or wrong,
If it's wrong, to set it right;
A land where all are equal
The house I want to see
Where all will have four freedoms;
That's America to me.