As far as I know, I'm the guy that started the "I Know You Rider" chain.

I found it in John and Alan Lomax's "Our Singing Country," arranged it, sang it a lot around Philadelphia circa 1959-60. Tossi Aaron learned it, put it on an LP, it circulated, a bunch of people started singing it. It subsequently got picked up at the Martha's Vineyard hoots and James Taylor seems to have learned it there.

Lots of others have put it on record since. So far as I'm aware no earlier version was in circulation before mine.