I am going to summit a list of seeds I have in early November, time enough to gather the 23 crop of seeds in. You should have 15 or 20 seeds in individual packets labeled with germination percentage ( optional ) to send in bubble wrap envelopes, USPS can be brutal. More than 20 seeds is just a waste seeing the grower will have hundreds more the next season.
This seed exchange can work very well if each of you save seed properly. Example.
Gather saved seed from early fruit if possible that is the time plants flower at different times making for crosses to be less likely. Late is still ok.
Pick only perfectly ripe fruit for your seeds & dry gently & pack right away.
Be careful to save only OP or heirloom seeds as Hybrids' will revert at 75, 50 then 25 percent 2 true each year you grow them.
Watch some you tube video on saving seed & learn why we ferment Tomato seeds & not cucumber seed. It's a rewarding thing to own your seeds & not be tied to the Seed companies & hybrid's. Your saved seed is worth more than money, you can trade seed with other growers & make everybody ( but the seed Companies) happy. LOL.
Just remember, the gardener you send seed to must wait for a long time to find out just what you sent them then it's to late. I have sent & received seeds from fellow growers around the world it's a great time to be a grower. I have been growing since 1971 & never have I seen a more diverse variety of fruit & vegetables available to backyard growers. Of course the Internet has done more to spread seeds around the world than the birds have.