Potatoes are among the easiest grocery store items to grow and multiply.
Every head of garlic you buy in the grocery store can grow 10-12 new full bulbs!
Sprouting green tops from onions make fast and delicious green onions and scallions.
The green tops of many root vegetables (like this carrot) are edible, and they're fast and easy to grow!
A lot of grocery scraps can grow a second harvest.
You can grow many, many "slips" from grocery store sweet potatoes, which will give you many, many new sweet potatoes!
Whole dried beans and peas are basically just seeds--so plant them!
Turmeric is also a root and grows like ginger.
Yes, horseradish is also a grow-able grocery store root!