While we had originally thought that we'd do the relaxed thing and avoid assigned tables, after a quick poll of our friends we realized that most people would prefer being told where to sit. So we ended up with assigned tables, though not assigned seats.
This added an additional project at the last minute--figuring out how to let people know what table they were seated at. I decided right away that names were going to be on leaves. I bought appropriately colored paper from an art store and cut out two leaf shaped patterns from cardboard. I enlisted the help of a bridesmaid who traced the leaves, cut them out, and wrote names on the front and tables on the back.
My original thought was to have them hanging from a branch, but after realizing that would involve more work than I was prepared to dedicate to this project, I looked around for an alternative. I'd already requested that people collect acorns for me (they were originally going to be scattered on the tables) so I dumped all the acorns in a basket I found in my parent's laundry room, stuck in a few mushrooms I had lying around from Small Stump, and used the acorns to prop up the leaves.
Ta da! Project done in less than 2 hours. Total cost: $5 for the paper.