I also heard, from a fellow who knew Paul Clayton, that he had committed suicide. "Who's Gonna Buy You Ribbons" wasn't the only song that was swiped from under him. He discovered/collected "Gotta Travel On" (Done laid around, done played around this old town too long, etc) but it was rewritten to give it a more uptown sound, and Clayton never received either credit or royalties of any kind.
Now - this may be pure "fakelore" that I am making up out of whole cloth -- but my memory says that he may have also discovered/collected "Copper Kettle." But it's been almost 30 years.... I'm sure about Gotta Travel On, though.
My friend had the highest respect for Clayton as a folklorist and musician.