"I once sent Peter Yarrow the lyrics to this poem I found, called "The Lover's Task", Sugesting that he and the trio (Peter Paul and Mary) should record it. His reply was: "Riddle songs are out." A few years later these two kids who called themselves Tom and Jerry, changed their name to Simon and Garfunkle and recorded the song as Scarborough Fair. And yes PS takes credit for it."

Sharmagne, there are a number of riddle songs similar to Scarborough Fair, and several versions of Scarborough Fair. Paul Simon learned the version he recorded (minus the added bit sung by Garfunkel) from Martin Carthy. I was present at the time; Carthy and Simon were living in the same house.

Sidney Carter wrote Lord of the Dance to the tune of the Shaker hymn
Simple Gifts, and I don't recall him acknowledging the source. He may have learned the tune from Aaron Copland's "Rodeo". Copland, however, did identify Simple Gifts as his own source.