Here's a shot of wild crab that gives a sense of the leaves and thorns. As delightful as the flowers are, the fruit is another matter. Quoting from Pehr Kalm, via Wikipedia, "The apples, or crabs, are small, sour, and unfit for anything but to make vinegar of. They lie under the trees all winter and acquire a yellow color. They seldom begin to rot before spring comes on." They aren't quite that bad, but they are clearly not the first choice, even of wildlife. They have been used in cakes and jellies. Heck, if you can use quinces, you can use these.