craft mailing issues

[http://users.livejournal.com/_remains/]

since it's the holiday season i've been sending some crafts out with my christmas cards and i've been having some trouble, especially with the little one inch pinback buttons i stick in the envelopes. one person said that their letter arrived without buttons, just a hole where it seemed like the letter had been tampered with. i received another complaint like it today.

does anyone know of a safe way to send craft items like buttons? is it because they are metal? i suppose in the future i'll pin them to felt or something, but i really am getting pissed off with this. anything you could tell me would be great!