Do you have a photo that is clearer or can you upload a higher resolution of this photo?

Generally where are you, such as city and state? That helps narrow down the possibilites since folks post here from all over the world.

Going by your description and the photo it sounds like a spurge,, a Euphorbia species. They are all quite weedy. They have a long taproot that you must dig or pull out, otherwise they will grow back if you only remove the top growth. Try to remove them before they go to seed or you will have countless more. Compare with Euphorbia/Chamaesyce missurica.

I think you're correct, Jay. Spotted spurge. I looked at online photos after you gave me the lead to follow. Thanks.

It's definitely a member of the Euphorbiaceae and a weedy one at that. But it is unfair to categorize them as "all quite weedy". They are not. This is an enormous genus with incredible diversity and many euphorbs are desirable garden plants and many are grown as tender, non-hardy houseplants. With over 2000 different species, only a small handful are considered "weedy".

Spurge is a common name for almost any euphorbia, not just the so-called weedy ones. "Euphorbia is a very large and diverse genus of flowering plants, commonly called spurge, in the spurge family (Euphorbiaceae)."

And the comment made was "a Euphorbia species. They are all quite weedy." There was no distinction made between the plant in question and any other euphorbia species.

Euphorbia missurica is not the same as Spotted Spurge. The latter is Euphorbia maculata.

Here are more photos of it. I am in upstate east-central New York State.

This plant may be a close relative which is growing near the first one I submitted. It has similar looking leaves and flowers, however, it's growth pattern is low and matted.

Euphorbia maculata (?)

Thanks for the IDs, Jay!

You're welcome debodun!

Also compare the more upright one to E. nutans.

Some look so similar, it's difficult for a non-experienced gardener to tell. Any info is appreciated. Thanks.

Debodun, I looked at them again and Tiffany is correct. The plant I identified as polygonifolia is actually Euphorbia nutans. They are actually easy to distinguish. Your plant definitely has serated leaves while polygonifolia leaf margins are completely smooth. I overlooked that somehow.🙊🙈

Thanks, again.

You're welcome, again, and thanks Tiffany!

Happy to suggest. ; )