Hmm, that first one is interesting, or at least not quite familiar to me. Can you get a picture of a leaf or two, spread them flat on a counter or board so we can get a good look at the pattern. Looks kind of like a Chrysanthemum. Also, I'm afraid the photo of the flowers is a bit fuzzy, any chance you can get a cleaner shot?
First one is "tansy ragwort" - get rid of it.
Second is some sort of "fireweed" or "willowherb"; harmless, and may be palatable.
Third could well be a dandelion; there is a great range in leaf shapes. I would wait and see.