@Trish &
@Dave, I would also be interested in hints from people more experienced with what to do if the majority of the people who show up are looking for freebies & have absolutely nothing. I don't mind people showing up without anything because they're new to gardening. After all, most gardeners love to share. However, I've tried to hold a swap before & the few people that showed up had NOTHING so it was a bust. If everyone shows up with nothing, what's there to swap?????