I love "Oh, Babe, It Ain't No Lie," too, and have been playing it forever. For whatever reason, I much prefer it to the better-known "Freight Train." I
only know the two verses and one chorus, and while I would be glad to know of more lyrics, I don't believe there are any. Some people sing one verse first (and usually third, to close) while others use the other verse first, and there are of course minor variations, but I've never heard any other "third" verse.
For a transcribed interview with Libba herself, with an interesting story about the song's origin, see:
(Scroll down -- the story appears after the lyrics, under the heading "Background.")
People talk about "Cotton Picking" as though it were an established style, but has *anyone* every done it like she did, i.e., playing the treble melody with the thumb and the alternating bass with finger(s)? I doubt it.