The one in the photo's center looks like Lamium purpureum (Purple Deadnettle). And just a guess - the one to the left, with the long leaves, may be Bignonia capreolata (Crossvine). That one is usually a high-climbing species, but does start out as single-leaved plants tight to the ground. It also has lobed leaves, as shown, and stays green for most of the winter.

Thanks for the speedy reply. I'm trying to figure out what everything is so I know how to care for the plants. (And also to figure out what is "weeds"/harmful/helpful and what is not.)
Thanks again.

I think the foliage is not right for Lamium.
Does it sting? It looks like the annual or small stinging nettle, Urtica urens. Often growes along annual flowers and veggies and self seeds

Ooh, yes, it is a small stinging nettle. That's exactly what it is. Have confirmed by getting "nettled" by it by accident a few hours ago. : / And also by comparing to other pictures of small stinging nettle.
Mystery solved. Thank you!