Currant, perhaps?

My thought also.

Interesting. It does look like some species of ribes. As I recall it isn't thorny, are all the ribes thorny? I guess I'll note it as non-invasive and see what it does this year.

I agree it looks like a Ribes. And no, not all Ribes have prickles. Red and black currants don't. Some Ribes flowers are inconspicuous dangling greeny white affairs so you might well miss them.
But I am puzzled by your description that it 'Comes up late in the season and is still green here in the early spring in zone 4.' Ribes doesn't 'come up' it is a permanent woody shrub. And it is deciduous so would lose its leaves and leaf out in spring, not 'still' be green. Those leaves don't look evergreen. Is that what you were implying?

Motherwort? Are the stems square?

Looks a lot like Garlic Mustard (Alliaria petiolata) judging by the leaves.

Central leaf grouping in particular is clearly elevated above the other foliage around it and therefore presumably not resting directly on the ground.

I know garlic mustard as I have been working on eradicating that in the woods for the past two years so it's not that. Garlic mustard also have fairly pointed leaf tips and is a more delicate leaf than this. I think it is a ribes and will keep an eye on them and see what they do this spring. Can't check them now as we just got six inches of snow.

Flora_uk, I missed your response. They really didn't come into their own until later in the fall. The stems aren't at all woody that I can recall, but they may be new, not older plants that would have established themselves. They are also pretty small. The leaves are about 3/4 or 1 inch I think. They did not loose their leaves over the winter, but rather stayed green throughout our pretty intense winter (we have snow cover but drop to well below 0). Nothing else in the woods has residual leaves. They may drop them now that it is spring and start new growth but I'll have to wait and see.

What I found curious is that they stayed green while everything else in the woods died or dropped leaves.

I was going to suggest motherwort as well since the new foliage in the spring looks more rounded and atypical for the foliage seen throughout the rest of the growing season. It is very cold tolerant - often one of the early bits of green I see in the spring. I'm not positive it is motherwort but it is a possibility.

FataMorgana

I'd have to say it looks more like one of the native alumroots (coral bells) to me - Heuchera americana, for example.

Tiarella species?

A shot of the stems would help. Can you do that?

I can't right now due to the six inches of snow that we got over the past couple of days. It should all melt in the next few days hopefully. My tulips were just starting to come up but looks like spring is going to be delayed around these parts.