I have used the top half of an onion, and put the base up, intending to use it later, and soon find a base with green onions growing from it, in the fridge.
I have also taken celery, and cut most of the stalks off, and have the base grow more. A lot of times, I take the tough stalks, and the base and use them to flavor soups, so I save them in the fridge, or freezer.
If I think that I will use them soon, then I don't freeze them, and that is when I often get sprouts. Now I do it on purpose to get green chives in winter! Also the little celery tastes great on a salad.
I have wondered, what if I planted this root base, it is growing, what would I get? Another experiment.
Talk to your plants.... If your plants talk to you... Run!