Garlic scapes are the flower stalk of the garlic plant, and they're trimmed off when they appear in order to keep the garlic's growing energy focused on the bulb.
They're edible as well, and can be stir fried and such. Mine are probably pretty tough, since they've been growing long enough to curl back on themselves a couple of times. I've read that they're tenderest before they start curling.
I think I'll use these to flavor my bean soup today, and then I can fish them out if they don't get soft enough to eat while they cook.