(try clicking on each picture to see the details better)
Circaea lutetiana; Onagraceae (evening primrose family)
Not in the nightshade family (Solanaceae), despite its common name. I believe the generic name (Circaea) is from Greek mythology; Circe was the enchantress who turned Odysseus’ crew into swine.
Another plant I was ecstatic to find. Set up the tripod and got out the 105mm lens and spent a good 10 minutes trying to get decent pictures. Why ecstatic? Because I’d read about it but never seen it before. Last year when I was even less good at using botanical keys, I (briefly) mistook another plant for this. Look at the closeup; how many petals do you see? It looks like 4, but is actually two (and two sepals). There are very few flowers with only two petals. Only half a page worth in Newcomb’s. That kind of trivia makes it interesting to me.
Here’s the whole plant, about two and a half feet tall: