Canceled Checks?

[raptorbill]

I was at my friends house the other day and he likes to collect canceled checks. He would take the check and matte it with a photo of the person. I was wondering how I could get canceled checks and what people will send them to you. My friend says that he writes a letter to the person asking for one and then they send him one. What people are known for sending them out??? I would love the help. Thanks.