Nope. Potato flower.
But you gotta love that bright yellow, cob-shaped stamen. I've never seen such a thing before, since this is only my second time growing potatoes.
The first time, I was in grad school. I hacked up a couple of supermarket potatoes with eyes on each piece, stuffed them into the dirt, failed to water, went to classes, wrote papers, and: potatoes happened. I never did notice any flowers, and the potatoes themselves were so small and stunted and runty from neglect, they were about the size of marbles. But, oh, the flavor was pure earth. I was enlightened. I learned something about the taste of one's own garden (and that's about all I learned, because I dropped out of grad school as soon as I met Cranky there).
This time, I've planted fingerlings from the lusty eyes of some of David Little's local potatoes. They could hardly wait to be planted, spurting skyward greenishly in the kitchen pantry. So in they went.
But then, what? How do you know when a potato is ready to be harvested?
El, at Fast Grow the Weeds, tells us that new potatoes (the little baby shaggy ones) can be dug up on her birthday. Which is today (happy birthday, El). To further refine, she says "two weeks after they flower," which for my tiny crop will be about mid-July. However, I'm reluctant to dig up baby fingerlings. What if they are microscopic?
To tell the truth, I probably will root around in the earth in a week or two, just to see what's happening down there. (It's called "grabbling.") Then I will wait until the plant tops die back and finally harvest the mature little spuds, when they are as diminutively grown-up as they will ever be.