I never really understood how a Round Robin works. Care to explain that, jaynine?

Sorry, I didn't see this post until just now.
Round Robins can be run in any manner of ways: most of the ones I've been involved in entail sending 'x' amount of packets to the host/hostess, including return postage & a return address label. When all participants' packages are received, the host/hostess then sorts them out (most try to accomodate the participants' wishes in what they'd like to get back) and mails them back to you. Almost every time you end up with more packets than you send in. Other RR hosts assign partners among the participants and they mail packages only to each other. Still others might include a box/package filled with seeds by the host & mailed to participant A, who will remove items they'd like to try, replenish with seeds from their stock & mail to participant B and so on, with the package ending up back with the host. Hosts usually post 'the rules' when they begin a thread or email all details to you when you sign up. If you ever have questions concerning particular Round Robins, any host would be happy to answer them.
Oh yes, some of them are only open to 'members' of their particular group.
Hope I've helped.