Ursula, that would be very disappointing !!
I'm not sure if this is a well-known fact about potatoes, but I only learned it a few years ago so will mention it here: when you plant your "seed potato," all the potatoes that plant produces will be above the level of the "seed". Hilling soil (or straw, or whatever) around the plants as they grow taller will encourage them to put out roots along the stems and form more potatoes. Don't allow potatoes to show through the top or the skins will turn green and bitter.
