I once found a cassette of racist music at a flea market. I forgot the name of the artist/group, but I listened once to the Godawful lyrics and threw it away, it being every bit as bad as I'd feared. Judging rom that one, they might still be looking for their muse.

In Nick Tosches' book "Country" (1977, revised 1985), in the chapter called "Cowboys and Niggers" which discusses interaction between black and white musics, on pages 215-216 of the later edition, music
on the KKK label in the 1920's and Reb
Rebel Records in the 1960's, where Johnny Rebel and James Crow recorded songs like "Some Niggers Never Die (They Just Smell That Way")is briefly discussed.