To Kill a Mocking Bird Chpt. 10+11

I never knew an old lady could be so cruel and rude. I feel bad for Jem spending so much time with her for a punishment but it is sad that she died. But what did she give Jem? I never really understood what she gave Jem. Also, what was wrong with the dog? Why did Atticus never tell his own children about his marksmanship? Is there something he is hiding? I am excited for the court scene though.