"While Azizi's point is well taken, it also isn't very well flushed out. Yes, race was used by collectors and folklorists to attribute origins of songs to European Americans that should rightly have been attributed to the US slave culture, but that culture included both African American slaves and European American slave owners and the culture of the antebellum south."

To flesh (or flush) out the guest's point a little more, remember that African slaves worked side by side with English, Scottish, Irish and Welsh indentured servants in Virginia, the Carolinas, etc. in the 17th and 18th centuries. Certainly these people shared songs and stories from time to time. 18th century religious revivals provided further opportunities for interchange. Impossible to prove, but I think a good argument could be made that a fair amount of the untraceable, anonymous melodies and floating verses in American folk song (both black and white) have there roots in this interchange.