Are there any onions that will stay a bulb if left in the ground? I would like to have an onion patch that I can always go to for dinner, but I know that probably wouldn't work with the biennial onions.

Walking onions are cool for onion greens, but I can't imagine caramelizing the bulbils. Would potato onions work for a permanent onion patch?

Also I read that some (not all) grocery store green onions are potato onions. Has anyone tried growing green onions? I've only found potato onions for sale at one place online, and I'd rather take advantage of a grocery store find if I can.