it appears that what he did sometimes was assume that whatever note he was singing in the melody was the root of the chord in the accompaniment, so that if he's singing "Midnight Special" in C, and he's singing an E note, he backs it with an E chord.? It can result in some weird effects.
Stu Herrick, who operates the Folkstore, commented on Jim Baxter's guitar back-up that he sounded like "Riley Puckett on Ecstasy". Thinking about it, I realized that both Riley and Jim Baxter were Georgia guys, and they really do sound like they heard each other--maybe knew each other.
The Weavers' cover was awful by comparison