This time of year, if you have any onions in storage, some of them may start to sprout. Before long, they aren't very nice to use, but you don't have to throw them away! See here? This is from yesterday evening. I put the sprouting onion into a small glass of water:
Now, look carefully... you can see that this morning the roots are already starting to grow! At least for a while, the onion top will continue to grow and I can snip the greens off and use them for cooking - omelets, soups, salads, whatever. It gives me just a little jump on Spring!