It was definitely a chapter book for young readers.
It must have been about an Appalachian or Southern girl who was very poor. She brought her lunch to school and the teacher snuck beetles into it from under the sink so that the girl would be forced to eat the more nutritious school lunch.
The girl also borrowed a library book and by accident dropped it in a mud puddle. She was so freaked out by having ruined the book that she threw it into a pond or lake.
Sorry that’s all I remember, but now it’s bugging me! Thanks for any help.