Growing Potatoes

Growing Potatoes

I found some potatoes that were under my cabinet and they were already growing, so I thought that I would plant them. The problem is that I'm not sure how to plant them. I feel foolish asking this but are these the tops or the roots? Can anyone please help? I've enclosed a pic so you all can see what I'm talking about. Thanks Photobucket
serviceberry

serviceberry

The view you have when you look inside my room

The view you have when you look inside my room

I rearranged and redecorated

I rearranged and redecorated

Giant Timber Bamboo

Giant Timber Bamboo

Plant ID question

Plant ID question

Current state of (container) garden.

Current state of (container) garden.