Update 2: Good Old Boy: A Delta Boyhood

 

There's another, young black boy in faded bibs at 4 minutes (farm scene). I only have seen a 3rd of the movie, yet.

The author Willie Morris also wrote My Dog Skip (rating 7) a similar 1940s Mississippi book/movie. There's also a book sequel: Good Old Boy and the Witch of Yazoo. I think the books are autobiographical (a thin white boy). Obviously no mentionings of bibs in the first novel.

The fat boy is called Bubba, played by Devin Ratray ("Home Alone", "Litte Monsters").

https://biboverallsfilms.blogspot.com/2011/03/good-old-boy-delta-boyhood.html