Most are picked up. I found 3 in one box, ONCE, those are the only ones I've found in the wild. Most are caught by the magnets, because I've gone through dozens of boxes and that's it.
They are a hard find, maybe because they are so easy to notice that a lot of them have been pulled already besides the magnets getting them. I think I have found 5 or 6 and 3 were at one time. I got one in a dime roll one time that I think was a MWR. Keep looking and you will come across one sooner or later. HH