Chamaecrista nictitans - Sensitive Partridge Pea?

Phyllanthus I think.

https://www.google.com/search?q=Phyllanthus+leaves&client=firefox-b-1&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj1k4-13q7dAhUCbawKHRnMBjQQ_AUICigB&biw=1920&bih=938

Yes, that one is Phyllanthus urinaria, since it lacks leaves on the primary stem, has flowers on short pedicels, and staminate flowers toward the tips of branches.

Ahh, the 2nd pic was not there when I responded. So many of these look similar with just the 1st pic, for me at least.

Thanks, everyone. Peren.all, I edited my message to add the second photo a few minutes after originally posting. And honestly, I was kind of hoping it was partridge pea, but it sure looks like Phyllanthus urinaria, and I just pulled it out. At first I was wondering how a weed of the tropics and the southern US ended up in my garden in Boston (I garden in a lot of flower beds in the area and have never seen it before), and then I realized: the seeds probably hitched a ride in the package of Gladiolus nanus bulbs I planted in spring of last year. The plants were growing right next to and even inside the glad. So it goes to show: anything you get from a nursery has the possibility of being contaminated with something, so be careful.

I hope I got it out in time. I convinced myself that those were flower buds hanging down on the pedicels but now I'm not convinced they weren't fruits. I'd contact the grower of the gladiolus bulbs, but what good would it do? They're doing the best they can, and I'm sure their procedures for quality control are no different than anyone else. Thanks for the heads-up, everyone.

The weed is often commonly called Chamberbitter. A real pest.