Context doesn't give anything of what Pee-Dee means in the song. Possibly just initials. But I introduced the card game Peedee to Britain in the 60's. It became quite popular among folkies & is still played, I understand. I learned the game from students at the University of Connecticut where it was of ancient tradition as a student card game. I've never encountered it elsewhere.

President Taylor and I did considerable research into the name, including the above-mentoned river & some other similar-sounding place names. But we never found anything.

It didn't occur to me to look in a book of card game history (there are several) until the 80's. There it was. Variously called & in many variations, it's a relatively mainstream version of Pedro (or Petey or P.D., you see) "The Game of All Fours" is a version of this, too. It was once very popular and a forerunner of Bridge & other thump games. The many versions & names show the great popularity it once enjoyed. We don't usually think of card games in considering folkprocessing but it's all the same, of course.

Anyway, maybe Little Pee-Dee was a great card player...