This is Jem's pants that are hung over the fence.

Jem waved my words away as if fanning gnats. He was silent for a while, then he said, "When I went back for my breeches--they were all in a tangle when I was gettin' out of 'em, I couldn't get 'em loose. When I went back, they were folded across the fence...like they were expectin' me."
Pg. 78