M.J.
Religious stores have all kinds of stuff. You could get a cross to hang on the wall of his room or a medal with his saint on it. There are also sports-related medals and statues if there's a sport he's really into. Another idea is a nice children's bible or a rosary. Books would work too, you could get a book of saints or about mass or something else.
If there is a religious store in your area, that would be the best place to go as they have tons of stuff and I have found the people there so helpful. My favorite place is Morning Star in Lombard, but I don't think that's close to you.
M.