Centaurea cyanus leaves are quite variable. These are Centaurea cyanus plants with leaves that are less lobed.

My three species of ironweed are not yet visible above the ground. That might help (z7a).

As far as I know there aren't any Ironweed species with lobed leaves like that

And Ironweeds are perennial. They wouldn't look like that in March.

Okay, not ironweed. Any idea what it is? I don't know whether to pull it out or not.

It's a Cornflower, Bachelor's Button, the scientific name is Centaurea cyanus. The leaves can vary in shape from plant to plant. They can be unlobed, slightly lobed or heavilly lobed. My Ironweed also emerges late. I thought it had died last year, but it was just very late.

almost unlobed leaves

Heavilly lobed

Both are Cornflowers, unlobed and slightly lobed

Yes, Jay said above, it's a cornflower. "These are Centaurea cyanus plants"

So I have two different kinds of cornflowers in the same bed? Weird! Some are blooming now, but they look quite different from the plants I was inquiring about. Thanks, everyone! I'll leave thenm alone.

No, not two different kinds. All the same kind, just with natural variation in leaf shape and growth. They're seed grown annuals, not clones, so there's going to be variability.

Well, this is all very interesting! I grew them from seed last year and they never died back. They started blooming again in late February. Some of them have really thick, gnarly stems and are crowding out my iris plants, so I've cut those back.

Thanks to all of you! You're all so smart and quick to respond.