This plant is growing in several containers so it's probably something invasive... I thought it might be some kind of senna or partridge pea, or sensitive plant but can't find any that have nodules on the back of the leaves like these.

Anyone know what it is?

Phyllanthus urinaria/Chamber Bitter
What an interesting plant!

commonly called ''little mimosa'' here

Quite invasive.

Thanks so much for the ID!

I wonder where it came from since I've never noticed it before. Although, apparently it can lay dormant for long periods of time and reseed like crazy! Both of those things seem to have happened here. It does have some interesting medicinal qualities.

Little mimosa. So, Cinda, that means you have it growing where you are. I'll have to look and see if it has any other benefits such as for wildlife before considering what to do with it. Although I should probably eliminate the problem now...

I wondered the same thing. We have been here for almost four years and it didn't appear until last year. But, that was long enough apparently, as it has spread all over a section of the yard.

Uh oh! Hamwild for that info!

I had it pop up a few years back and had to look it up , only a single plant , but that same year I visited a large community garden and saw it everywhere like pig weed does here so I yanked the little mimosa out and burn piled it so as not to have it seed
I am pretty tolerant of weeds but wasn't in the mood for one more that year