One of the waterleafs? Virginian Waterleaf?

look for small pale blue/violet flowers in late spring.

Here is a link that might be useful:

Thanks for your effort, but I don't think that's it. To me, the illustrations in your link don't look like my plant.

It reminds me of Phacelia bipinnatifida, but I don't know that it is considered a ground cover (unless it is seedlings). It is a biennial, which means that it puts out growth the first year and flowers the second (sorry if you already knew the definition!).

Here is a link that might be useful: Phacelia bipinnatifida

Looks like Phacelia bipinnatifida, another Waterleaf, also known as Scorpionweed. Its a biennial, and has lovely blue nodding flowers in early spring.

Here is a link that might be useful: Fern-leaved Phacelia

Thanks esh_ga and Phylla. Actually, I'm familiar with purple phacelia, but didn't recognize it at this stage. In our area it has distinctive white centers in the purple flowers. Does anyone know why it's also called scorpionweed?

The name Scorpionweed refers to the flowers, a "scorpiod cyme", meaning the inflorescence is a unilateral raceme that arcs downward, like a scorpion's tail. (Being a Scorpio myownself, I see no negative/poisonous connotations here %^D )

To add "Phacellia" comes from the Greek word phakelos, meaning cluster.

I will say that Phacellia is an enjoyable addition to a woodland naturalized planting. It adds great winter interest with the nice green first season rosettes, and the flowers aren't showy, but nicely cheery early on in spring. It tends to travel around the garden, but ebbs just when other plants are getting their groove on, and disappears until fall, when yer happy to see that green again.

What you have is Artemesia vulgaris also known as mugwort. It is extrememly invasive and will eventually take over any place it's growing.It's a tough plant, hard to kill and spreads by root and seed.It's considered invasive in several states including Tennessee. There is a native species but I think what you have is the introduced one.
It's interesting that you've noticed it growing along the railroad tracks, one of the traditional uses of mugwort was to protect travelers.

I have Phacelia bipinnatifida in the woods behind my house, and it doesn't look like the plant in the picture. Phacelia foliage, in addition to not being as deeply and irregularly toothed as the leaflets of the above plant, displays unmistakeable and striking silvery patterns on the leaves of the wintering rosette of foliage. This silver patterning disappears come spring when the plant grows up, out and then blooms.

I second the artemisia ID.

Soeur

It doesn't look like any Artemisia I've seen.

BHPGuy, I believe the key to solving this may lie with your first statement.

"This stuff comes up every year about this time."

Could it be a Dentaria or something closely related?
These emerge in fall and are summer dormant.

I'm somewhat familiar with mugwort, and toothwort, and I still tend to favor the phacelia id. We have profuse amounts along the tracks in spring, and I believe this is the early stage. I'll certainly take a closer look when I fish tomorrow. Thanks for all of your help, this board has been a revelation.

If it is indeed profuse, and you have access to known plants of Artemisia and Dentaria, dig up a chunk of each of them and compare the underground structures. You'll find differences and similarities, and learn more about each.

Science at its best: investigate what is available first-hand, and send pics of what you find so that the rest of us can build upon it.

All Artemisias have a smell. I can't discribe it right now, but many times during a walk, if I pass Mugwort or
wormwood, I'll tear-up a leaf an smell it. This habit keeps
my nose in tone. Some plants like, Cherry, Sassafras, wintergreen, and Artemisia can best be IDed from thier scent

We have profuse amounts of toothwort and purple phacelia. The only mugwort I have ever found is next to my driveway, one specimen. It's dried up now, no new growth at the base, hopefully I can remember which stem was the mugwort.

The root photo idea sounds interesting, but I've lost the battery cover to my camera, so I'm dead in the water until I get the part, maybe a few weeks. I'm personally convinced that what I have is phacelia, because I see a lot of it along the tracks in the spring.

Got my camera part! Those Canon folks are on the ball. I had to buy a tiny screwdriver to install it, but now I'm back in business. The first 2 photos are toothwort. My Audobon guide mentions that the roots have tooth-like projections, and that is what I found. Hopefully it shows up well enough in the photos. When I first started noticing this stuff this time of year, I thought it was wild strawberries.

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The next photo is the phacelia, just a taproot grownig down through the ballast by the railroad, trying to reach soil. The toothwort was in humus next to the ballast.

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While I was up there I got a photo of the witch hazel that's blooming right now. We have something blooming every month of the year.

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Alas, I couldn't locate the mugwort that was blooming by my driveway in the summer. I recall it had chrysanthemum like leaves (which is why I first noticed it). The stalks and leaves are dried up, and I couldn't find anything that looked like chrysanthemum leaves. I'm still convinced what I have is phacelia. Thanks for the root suggestion.