Feeling really guilty

I was with my mom at the mall today, and as we were walking through the entrance we noticed a purse on a little counter at the payphones. No one was there, so my mom just took it. I told her to leave it, or give it to customer service, but she wouldn’t listen. Then, she went into the washroom, and a couple minutes later comes out but the purse isn’t with her. I ask her what happened, and she said she took all the money and just left it there. $210 CDN+$3 US dollars. Then I ask her if she found anything else, and she says that the girl is on welfare because she found a cheque or somthing from the government. As soon as she said that, I had this really bad feeling, I mean… I stole from the poor. As we were walking through the mall, I kept telling my mom to give the money to the customer service, but she wouldn’t do it. Now I feel so guilty, knowing that someone lost all their important cards and money… :*(