For the early stuff, get hold of 'Hard Times Come Again No More: Early American Rural Songs of Hard Times and Hardships Vols 1 and 2' Yazoo 2036 and 2037. These are compilations of songs from black and white artists of the 1920s and 1930s and include classics such as the Bentley Boys' 'Down on Penny's Farm', Blind Alfred Reed's 'How Can A Poor Man (Stand Such Times and Live', Allen Bros 'Price of Cotton Blues', Barbecue Bob's 'Bad Time Blues' etc.

Cheers, Stewie.