you used to be able to buy tiny envelopes for school dinner money.. not sure if they're still around now. my kids get their lunch via a fingerprint recognition machine!
Alternatively Debsy you could go into your friendly neighbourhood florist (especially if you're a customer) and ask if you may buy some acetate envelopes roughly 3" x2", tell them what it's for otherwise they may think you're working from home!! The advantage with these is that you can see if there is anything inside at a glance.
Thanx MB, but some of 'em are so small - they fall out of the holes in the corners !!
(I usually use my old mail envelopes for scrap paper, like to write shopping lists on !!)