My apologies in advance for only having this one photo. I can take some more tomorrow if no one recognizes it.
It's blooming now in Northern Virginia (Zone 7a). So far, I've only seen it in roadside ditches.

Possibly Pycnanthemum virginianum ??? (Common Mountain Mint)
edited for spelling

It kind of looks like that, but Pycnanthemum bloom later in the year so that's not it. I'll post some better photos soon.

It sure looks like Pycnanthemum to me, my first thought was Narrowleaf Mountain Mint (Pycnanthemum tenuifolium) but it would be odd for them to be blooming this time of year.

How about Plantain-Leaf Pussytoes (Antennaria plantaginifolia)
https://gobotany.newenglandwil... Well, forget that ... the leaves aren't right for that one.

It looks to have four petals so I'm thinking maybe Brassicaceae, mustard family, if that helps anyone - so far I haven't come up with a match.

I object to Pycnanthemum for the same reason as Lin, timing, but there may be others that bloom much earlier, than the couple species I've spotted/ID'd in my area.

It looks close to field pennycress - Thlaspi arvense - but I'm not sure it's an exact match. Here's a pic:

https://www.google.ca/search?q...:

I think you might be right, sooby! Here are a few close-ups.

The seed pods are the most recognizable feature of this plant, in my very not-expert opinion.
Field Pennycress (Thlaspi arvense)

If a consensus is reached that it is T. arvense, the entry in the database here could use your pics!

The second picture shows the somewhat pointy margins that Thlaspi arvense should have and which I couldn't see in the initial picture, so I still think it's a potential ID. But, as Tiffany said, it should be a consensus determination because I don't know if there's anything similar that it could be confused with.

I concur, it sure looks like Field Pennycress to me too. There are some great photos for comparison on these pages:
https://ipm.missouri.edu/IPCM/...
http://www.illinoiswildflowers...
http://fieldguide.mt.gov/speci...

Thanks for all of the great research, everyone! I think it is Thlaspi arvense.

The Missouri.edu link above says that "Field pennycress plants may be confused with those of pepper grass (Lepidium densiflorum), but the leaves of pepper grass do not clasp the stem and the flower petals are shorter than the sepals."
The leaves on my plants definitely clasp the stem, so that rules out at least one look-alike plant.

Now that it looks like it's a non-native invader, I'll pull some up to get better photos, and I'll be happy to contribute them if people agree on the ID.

It can't invade unless/until it drops seeds. Waiting to get shots of the seed pods would be "safe."

It also looks similar to corn salad, which grows this time of year. Mine is just starting to flower. Corn Salad (Valerianella locusta)

https://www.google.com/search?...

wildflowers said:It also looks similar to corn salad, which grows this time of year. Mine is just starting to flower.

It does but if you can blow up the top picture of the ID plant, and look at the flowers on the right hand side, one can just about see that they have four petals whereas corn salad has more:

[quote="purpleinopp"]The seed pods are the most recognizable feature of this plant, in my very not-expert opinion.
Field Pennycress (Thlaspi arvense)

You're right, those seed pods do stand out. I'll try to get photos of some, but the plants are growing in ditches that might be mowed soon.

In the meantime, here are a few more photos:

a close-up of some basal leaves


clasping leaves further up the stem


and the roots

purpleinopp said:The seed pods are the most recognizable feature of this plant, in my very not-expert opinion.
Field Pennycress (Thlaspi arvense)

Here's a photo of the seed pods:

They're fatter than the photos of Thlaspi arvense seed pods I've seen online, but perhaps they'll be flatter when they dry out. ......or maybe it's not the same species.

Take a look at this plant as well:
Shepherd's Purse (Capsella bursa-pastoris)

Lepidium campestre is similar to Thlaspi arvense but has "fatter" seed pods although I'm not sure the plant habit is as close to the ID plant. I don't think it is shepherd's purse because that has seed pods that are more triangular.

Lepidium campestre:
https://www.google.ca/search?q...:

Yes, IDK if that shape develops as the pods age or they start that shape & just get bigger.