Symbolism, Imagery, Allegory
Early in the book, J.D. receives a real Indian beaded belt from Uncle Mark for his birthday. After J.D. gives Tom and Sweyn the mumps, though, they punish him with the silent treatment, which Tom agrees to call off if J.D. will give him the belt:
The belt was the envy of every kid in town. It was a stiff price to pay.
[…]
Tom got up from the bed where he was sitting. I watched him walk to my chair, remove the belt from my pants, and hang it on his chair. (2.121, 125)
Here we see just how much Tom controls the dynamic between him and J.D. He won't just end the silent treatment—he makes his brother pony up for it, taking his prized possession. If ever we doubt that Tom is kind of greedy, the belt makes it clear that he most definitely is. J.D. doesn't benefit at all from this interaction, after all.
On the flipside, months later, in the glow of good feeling Tom gets from helping Andy Anderson, he returns the belt:
I stood there bug-eyed as I watched Tom remove the Indian beaded belt Uncle Mark had given me for my birthday and hold out the belt toward me.
"Here is your belt back, J.D.," he said. "It is a little worn by now but still the only genuine Indian beaded belt in town." (8.358-359)
Tom's return of the belt is symbolic of his intent to reform completely. He's no longer intent on seeing just how much he can benefit from situations, and instead he now knows the value of goodness for goodness's sake.