I think I asked last year but never got definite answers. I got new pictures. I've never seen any flowers. They're different than the leaves from a dandelion weed.
those little white flowers look as though they are from some sort of bulb or tuber: in general, bulbs such as allium, daffodil, hyacinth, lillium are not supposed to be fed.
the first 3 pictures you posted do look like some type of lactuca or prickly lettuce, but the one w/the heavily serrated leaves looks a little different from the second two, almost like a wild brassica but it could just be a different species or subspecies. they generally look like edible stuff to me...you'll know if it's a brassica, as it will have flowers looking like some sort of wild mustard...prickly lettuce or lactuca have more of a dandelion looking flowerhead (but often w/multiple flowers)