Emily, have you found the Burl Ives autobiography? I think, from memory, it's called Wayfaring Stranger. In the 40s he had his own radio show with that name and I suspect that you could trace the source for most of the people who have replied here back to that show.
I've just found my copy but don't have time to re-read it right now.
But it starts with his birth, in Jasper County, Hunt City Township, a few nights after Halley's Comet made its appearance - in 1910??
Anyway, the songs he sang were often church songs and songs he learnt from his family and neighbors.
So he would probably have learnt Wayfaring Stranger sometime before 1920.
Cheers,
Robyn