It looks like Creeping Charlie. A ground cover weed.

Here is a link that might be useful: Creeping Charlie

Thank you, Jeannettemae, for replying.

Hmmmm. The leaves do look like those. I'm wondering, though:

What I have is growing in clump-like fashion, and not vining or crawling. Also, isn't creeping charlie Spring flowering? If so, why would have come up after it's season to flower?

Does it get a flower?

Creeping Charlie can start off as clumps before it sends out runners and in a pot it can look like quite the healthy clump so that is not unusual. To tell if it really is Creeping Charlie, just rub and smell the leaves. They will have that unmistakable Creeping Charlie scent.
Remy

Oops forgot to add, Creeping Charlie(and other weeds too) can pop up at any time. When they flower doesn't really matter, it is when conditions are right for them to sprout. For some weeds that seems to be any time above freezing, lol.
Remy

Thank you, funnelweb & Remy, for replying.

Funnelweb, No, it hasn't flowered. It's just green.

Remy, I know that the Spring wild flowers I've seen in our yard seem to show up mostly in Spring, and flower. I've not seen this at all, until it popped up a few weeks ago.

it has nice leaves, so I was hoping it would be something that would give nice little flowers at some point. If it is Creeping Charlie, I guess it'll just be green as it is, now.

The leaves on it are suddenly whitening a bit. Don't know why. Perhaps as they age they do that? Thought I'd mention in incase that were any indication of whether it is CC or something else.

" This showed up in a planter " - as many weeds and their seeds are transported from nursery stock to the home garden.

This is not something you want!

Here is a link that might be useful: Creeping Charlie

I don't think that is Creeping Charlie - Glechoma hederacea. The leaves look way too big and the arrangement is wrong. Not sure what it is, I would guess some kind of Lamium - some of them are garden plants and some of them do get whitish leaves. I think you'd be safe to leave it where it is or put it in a pot and see what it does.

WW

I also don't think it's quite right for Creeping Charlie. Did you crush and smell a leaf? It would have a very pungent minty odor.

I also would leave it to see what it does next.

I agree with weedwoman. It looks more like a lamium than ground ivy (aka creeping charlie, gill-over-ground, hedge maids, ale hoof, etc...).

Lamium or dead-nettle also have a fragrance to its leaves. Ground ivy has a bit more of a smell like tomato leaves and lamium is a bit more musky. Scents are hard to describe...

FataMorgana

There's still debate on whether my weed is garlic mustard or creeping bellflower... yours looks like garlic mustard to me, but I am no expert - I can't even identify the one I've got! LOL

{{gwi:252859}}

The easiest way to convince you it is garlic mustard is for you to remove a leaf, crush it, and smell. If it smells like onion and mustard.... then it is.

Thank you all, so much, for replying! It does have a scent when I smell a picked leaf. But, the smell is not minty, nor garlic/onion (although, that would have made sense as we had brought back garlic-mustard seeds from an outing last year). The smell isn't a nice one, IMO.

I'll have to smell my tomato plant leaves to see if it is similar to that, or not. I'll let you all know :)

Thanks so much!