Good question! I'll have to go take a closer look at the few green (bunching) onions I never pulled last fall. I have continued to use them all winter but I notice they are a bit more muscular looking now. (Especially since I put in some onion sets nearby.)
In the same general area I have a patch of oregano that wintered nicely and there are garlic plants coming up (I had a bunch of dried out little corm things that peeled off of last fall's garlic when it dried, and I poked them in the ground to see if they'd grow). I can't tell you how wonderful it is to brush past that part of the garden--onions, garlic, and oregano--it smells like an Italian restaurant.