Like Jim Waddick, I have a lot of experience with seed envelopes, because for three years in the mid-1990s I handled the intake phase of the massive NARGS Seed Exchange. People sent seeds in every imaginable kind of packet. One donor saved all her tea-bag individual paper jackets for this purpose. From eastern Europe we received carefully handmade packets, unfortunately often constructed of very fragile thin paper that seeds broke through. I myself use brown paper coin envelopes most of the time because they hold more than glassines and are easy to write on, but I agree with Jim that the paper ones have drawbacks. They often leak at the bottom and have to be taped, and if there is moisture in the seeds (e.g., Paeonia) they will lose their glue and fall apart. I keep two sizes of these envelopes handy, as the larger ones can be stuffed with whole capsules for drying and later cleaning, and then reused. I get them at office supply stores, but they're getting harder and harder to find, especially in multiple sizes. You can get glassines that are self-sealing, but I don't like them because the seeds can stick to the adhesive when you're filling or emptying the envelope. NARGS has now abandoned these for non-adhesive glassines that you have to seal with a glue stick (messy) or tape (tedious). Not all writing implements will write clearly on this type of paper; a fine-tipped Sharpie pen is best. Some seed suppliers send out seeds in little poly zip-lock bags, known as sample bags (you can get them from scientific suppliers or geological suppliers). I don't like them because the seeds stick inside the bags and have to be scraped out (a lab scoop is good for this). Also, if the seeds are not dry enough, they can mold and rot in plastic bags. The home-made "origami" envelopes Kathleen Sayce mentioned are good to know about if you find some good seeds and have no envelopes with you, but they're not well liked by people handling exchanges because they can fall apart during shipping and handling, and one doesn't know quite what will happen when one goes to open them. Jane McGary Portland, Oregon, USA