Horntoad said:
"I would be upset if I asked several people for a pack of seeds and was told "sorry you can't have it because there is nothing on your list that I want."
Your system is a trade system and the system that most of us are use to is more of a sharing system. I don't need to feel like I made a "fair" trade. If I can give away all my extras seeds that I have no intention of planting and come away with just a few that I really want then I will be a happy gardener.
I see where you are coming from and it is a noble idea. I don't discredit the notion of wanting to give up seeds that you no longer need...but that is why there would be 'donations' and 'freebies' allowed. Everything works alongside each other. Once people in swaps get to know each other and know who might be up for more random swaps, etc...they can choose to simply "freebie" or "donate" stuff to others with no expectation of something in return. You might get to your Trade List one morning and find out that Donald has offered to 'freebie' you a packet of 80 morning glory seeds. That's what will eventually happen once people get settled into their swaps and get to know the people in their swaps better. They'll know what others might like, they might donate, they might not. But the method I'm describing also includes people who might have seeds that they definitely want something good for.
I think I noticed someone with hybrid sempervivum seeds on their list. I know that if that were me, I wouldn't be satisfied getting common marigold seeds in return for that.
And consider the people that might only participate in a swap round once every once in awhile....if they bring all of their good stuff to the table and are 'forced' to trade it all off to people who have nothing they deem desirable in return...not only is it bad for them for that round, but they may not participate in future rounds, so they've given off their goods and never have the chance to get anything 'good' in return.