These are the scapes. They are essentially the flower of the garlic plant. In growing garlic, you snip the scapes off so the plant puts the energy into growing the garlic pods (or bulb) instead of flowering. Garlic scapes now appear in farmer’s markets and you can find recipes on the internet for cooking scapes. I have not tried eating them, but supposedly they taste milder than the garlic pod and the flavor is somewhere between an onion and garlic.
If you break open a scape (as in the picture above) or allow the scape to continue to grow on the plant, you will see a flower. Garlic puts out scapes before the leaves start to turn brown. It should be time to harvest the garlic in the next few weeks.