do not mail anything to anyone until you have received payment. If you feel so inclined you can offer seeds for free to anyone who will pay postage, sometimes members do that. But you should still not ship them until you are paid. Well there are some generous folks here who sometimes send out free plants and even pay the postage
(you know who you are!)
But no one here should feel obligated to do that. You do not have to buy, sell, trade or give away anything to use this site.