Please help ID my mystery weed

These have popped up in half a dozen buckets around my container garden. Unfortunately, most of them are in buckets where I planted food tree seeds of uncertain provenance (code for "eBay") and while I'm pretty sure it's just a weed, I'd like to ID it.

This one is in a bucket where I planted a strawberry crown from a dried-out bag I got at a big-box store. One of the other crowns in a different container actually came up, so I have confirmation of what I already knew a strawberry looks like, and I'm pretty confident this is not one. But I'd like to know what it is before I yank it and recycle the bucket soil back into my container-filling station. A solid ID will help me feel better about yanking the other examplars in my other buckets. (Given my habit of recycling container soil after failed germination experiments, I do sometimes get plants I wanted sprouting in buckets labeled something else, months or years after I gave up on those seeds.)



Thanks!

You will probably need to wait until it blooms to be sure. It's not a strawberry. But if you can find a plant ID site online, fill in the plant descriptors.

If the flower brings in beneficial insects it is worth keeping.


These are the details that will help find what it is.


The color of flowers, whether they are large or small and indistinct
The height of the plant when it blooms
Leaves are directly opposite each other, as opposed to staggered down the stem
simple leaf (one leaf coming off the stem)
Pointed leaves
Lobed leaf edges

Redidsh brown stem

Are any of them coming up in your garden where you have not disturbed the soil, volunteers, such as in the shade, where there are plants that need a lot of water, or where plants need very little water? If you have close neighbors, do they have this plant in their garden?

It reminds me of amaranth but not quite. Might wait for flowers as Cristo says.

You know, this looks familiar, and I'm going to guess it's a New Zealand impatien, what they call Sunpatiens, because they can take more sun than the regular impatiens that need lots of shade. Not full-on all-day sun in summer, but morning sun. They are very nice plants.

Common three-seeded mercury