Oh, I do take the roots and about an inch of a green onion and plant it, works great!
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Yes, this does work nicely. I've had the same ones from the onion family growing for years. Onions, chives, garlic, leeks, etc will all grow again and again for you. Maybe most of the underground family will, it's worth a try. Sure will save money in the long run.
Also grow sweet potatoes/yams for the leaves as well as the under ground plant. Lots of folks eat the leaves as well, just leave some on the plant to keep the underground part alive.
When the weather warms up, plant Taro/Elephant Ear's cousin or half brother. It can be found in lots of grocery stores, but makes a marvelous pot plant with the large leaves. I grow them for looks and eat them in the fall/winter. And can buy some herbs in the grocery store with roots still on them, so I cut off most of the tops and plant the roots. Plants are very adaptable and WANT to grow.