I was thinking of writing about this myself, but Gallimaufree has done a wonderful job of writing up how to use and eat edible flowers, including some recipes. This is a very interesting and useful blog, so you might want to check out many of her other articles. In the first entry she tells you how to eat flowers. In the next entry she discusses edible gardens--with a lot of great ideas for blending beauty with pratical, with a list of flowers that are edible and which aren't. Check it out!
PS. You might want to read how Gallimaufree got a duck stuck in her thigh. :) It's a remarkable story!