We love the idea of incorporated living things into your wedding. Seeds of Life has some incredible wedding favors that are earth-friendly and quite stylish. Be sure to pick appropriate plants that are going to thrive in your particular climate. If you have out of town guests possibly have an alternate eco-friendly wedding favor for them. Seed packets make a good alternative for those guests.
Plant a Memory also offers live trees and seedling packs for wedding favors. The below is $2.69 and might be a more affordable alternative.