After my potato plants flowered, small green balls are growing. What are they?

Maybe not potato maybe tomatoe

Hi! michiganman, and welcome to AMHD :)

Although the potato is usually started by cuttings or small potato starters. Those are the seed pods of the plant.
It's much easier to grow by the former, than the latter.

Pinch 'em off and the plant will send its energy into the tuber.

K