Buds of garlic that sprouted before they got used
buds of garlic that are leftover and won't be used
Onions, same as above
tomatoes that are too old to eat
Potatoes that sprout
Potato eyes
Sweet potatoes that sprout
Pineapple tops (May take 2 years to fruit)
Dried beans
Sometimes Avocado pits will sprout.
Things I haven't grown, but ought to work:
Malanga root