Have you ever noticed green marble size fruits amid the foliage of your potatoes at the end of the growing season? If so, these are the fruit which yield approximately 300 true seeds. Seeds like these are used by potato breeders to find potential new cultivars as each one is genetically distinct.
The edible tubers are actually enlarged, underground stems. Normally, most potato flowers dry up and fall off the plants without setting fruit. A few flowers do produce fruit. The variety 'Yukon Gold' produces fruit more heavily than most varieties.
Potato fruit, as well as the plant itself, contain relatively large amounts of solanine. Solanine is a poisonous alkaloid. The small fruit should not be eaten.
Just for fun, clean and save some of the seeds and plant them inside in mid-March. After frost danger has passed, transplant the potato seedlings into the garden and wait. See what you get! You may be surprised at how different the potatoes are from plant to plant.