It contains a fake, inactive card. I'm at school. My mom takes 10 minutes to text me telling me that I'm in trouble because she found it. She may as well have told me:

John, I have been illegally rummaging through your mail and found a fake credit card that I think is real. I'm going to tell your father like I always do because I can't do anything myself because I'm just a retarded housewife. No hanging out after school. Oh, and by the way, because it's legally yours, I will not give it to you.