This plant suddenly appeared in a 2 1/4" pot which had previously held a seedling growing from the NARGS seed exchange last year. I'm sure it's not the original plant. I didn't recognize it as one of my common weeds, so I have let it continue to grow. It reminds me in some ways of crab grass but the leaf blades are fairly broad and almost folded. Does anyone recognize it?

Curious little leaflets. It says to me that the mature leaf form is just starting to form. I don't have a clue....

No clue either. Definatly wouldn't place it in the grass family though..

Looks vaguely Coreopsis-y to me. Definitely not grass.

Looks like the leaves are going to be a little more complicated than they are now. Something Coreopsis was my first thought too.

Gazania rigens?

Thanks all for your input.
Here's the list of the seeds I planted from NARGS seed exchange.
I can't imagine it's one of them, since the sudden appearance of growth was 6+ months since planting.
Alyssoides, allysum, antennaria, anthemis, anthyllis, chaenorhinum, chimaphila, daphne, dianthus, globularia, iberis, phyteuma, salvia.
It's growing actively now (under grow lights in my garage) ... I'll just continue to monitor it to see what develops. I'll post a follow up as it continues to grow.

No, can't be any of those, although I am not familiar with chaenorhinum.

Incidentally, Antennaria seed is recalcitrant. I tried seed of A. rosea 'Nywood' from the NARGS seed ex probably 15 years ago a couple few times with no luck. It became a "conquer or be conquered" issue with me.

When the second round was instigated, the seed was (almost) always available and I'd always order it, as the seed is so incredibly cheap and no limit. Never any luck, until one came up this past season. Still have to grow it on to see if it is that, as I grow Gaspensis and confinis who's seeds "get away" and may have settled there and germinated.

Anyway, I did plant fresh A.r.ssp. confinis seed this year and they came up in about a month. I did save extra seed (dried) of confinis as a control to plant later. Thanks for reminding me, I still need to plant soome of them and give them a winter cold conditioning.

very interesting plant, and doesn't ring even the faintest bell for me.

Thanks for taking a look.
I'll close this thread for now, but may resurrect as the plant matures.