You are right, Bruce, that it is related to the Born About a thousand/four thousand/10,000 Years Ago family of songs. In my opinion, the definitive version is that of Charlie Poole and the North Carolina Ramblers recorded in 1925. Unfortunately, it is not on either of his CD reissues, so that means I have to dig through piles of records to find it. And then try to figure out what Charlie is saying! I did locate a quote from Norman Woodlieff, who was Charlie's guitar player on that session.

"There were some words that Charlie put to Man that rode the mule that relate to a true incident that happened up in the country by the North Carolina state line. A bunch of us were up there fooling with a mule and I got him and he went over to a pine tree and rubbed up against it so I fell off.
Charlie wrote the words:
'I rode up to the line
And I fell up against a pine . . .'
That's what that means."
Norman Woodlieff, from a 1972 interview by Janet Kerr