What did billy trap that caused his mother to spank him?

The only reference to spanking I recall is:

“Everything was going along just fine until Mama caught me cutting out of the circles of tin with her scissors. I always swore she could find the biggest switches of any woman in the Ozarks.”

Are you referring to a particular chapter?

Billy didn't trap anything that caused his mother to spank him. It says in the book that when he is cutting out circles of a tin to catch a coon with his mother's scissors his mother finds him. In the next sentence it says he is sore. When Billy does catch a coon he comes running back to his house screaming and his mother thinks that he was bitten by a snake and she gets scared. She says that if he ever scares her like that again she would beat him with a switch. I'm not sure if your referring to something else but that is all I could find.

It was the cat At the start of the book with the traps when he first got them he placed them around the barn and ended up catching the cat a bunch of time and he got spanked from that