Possibly a Boemeria but without a location that’s a wild guess.

Perhaps Boemeria nivea?

It should also be stated whether this is an indoor or outdoor pot.

i agree with Jay.

Here is a picture of a Boehmeria nivea:

Leaves are not the same.

it was found outdoors, first day frost 3 days ago, I moved the pot inside... not sure what to do with it not knowing what it is. @floral - BC Canada here..

did you put it in the pot.. or is it a rogue seedling growing in the pot of another plant ...

What I've thought from the start is that probably it's an Amaranthus and that continues to seem likely.

I thought of Amaranthus too. Do their blooms look like that when they start? OTOH, I read that there is a lot of variation within Boehmeria nivea, including at least 1 subspecies. Leaf arrangement can vary in Boehmeria nivea. This amaranth/acalypha leaf also looks pretty close. Whichever plant, it should be obvious in the next few days, when the flower matures.

Notice that this time the leaves are the same.

It reminds me very much of a weed I have here - I recall posting a query on this forum, and getting an I.D., but now a search yields no results.

Here it is gone to seed, and color is not accurate - too much sun...

P.S. Finally found it:

https://www.houzz.com/discussions/5886824/new-mystery-to-me-weed-gulf-coast-fl

I.D.ed as Acalypha arvensis

I didn't put in the pot, it was self seeded this summer, the pot was indoor last winter.