These are metal "nests" with an egg being protected. Three leaves add to the tree symbol and the whole charm is attachable with the little garment pin attached to the tag.
The "birds of a feather flock together" was the idea behind the button trades. I thought it would be fun to find your "flock" by looking for those who have the same bird "song":)
My final trade is an ATC made from a handcarved rubberstamp I made at my summer play dates with my friends at Art Zoo.
As soon as I can figure out why I can't upload more pictures, I'll do a followup post with images for the two art pieces I'm planning on submitting to the Artfest gallery show.