Thanks, Rick.
I did sow two types of corydalis, but not on that same day. I was careful to avoid cross contamination of my plantings this year, but even if I had none of those started that day seem to fit. The anemone is furry, so I cant see it being that one, and the rest are either up in other containers or are pretty much known to me by sight.
These are the ones I started that day:
Streamside Lupine (Lupinus polyphyllus)
Amethyst shootingstar (Dodecatheon amethystinum)
Columbine (Aquilegia vulgaris 'Clementine Salmon Rose')
Papaver somniferum 'Drama Queen'
(Anemone patens var. multifida)
Fragrant Persian Stonecress (Aethionema schistosum)
I'm thinking it might be a seed that got into that packet unintentionally.
The leaves kind of remind me of a bleeding heart that I have here, but I've never started seeds of those so...