I doubt you'll find seeds of the Cardamine, this because it is a very common weed. Around here, it's now in full seed, spewing them as far as 6-10 feet from the parent plant. Perhaps you can collect your own seed.

Dear Jean,
I don't even know what it looks like. Will look at my WA wildflower or plant book. Thanks so much. I really think people here should treat some weeds as plants. I suppose someone will snap at me, but I don't really give a hoot.Open up a little. Chill out.

Being me,
Al_compost

According to Jacobson, WILD PLANTS OF GREATER SEATTLE Cardamine flexuosa, C. hirsuta and C. pensylvanica are common weeds here, whereas C. hirsuta ssp. oligosperma is "relatively rare". He does not list Lepidium montanum at all; common ones here are L. virginicum var. menziesii (on saltwater beaches) and L. virginicum var. pubescens.

Mr. Compost, usually of the butterfly forum,

The World database lists these hostplants for A. sara,
the Pacific or Sara's Orangetip.

Arabis glabra
Arabis perennans
Arabis platysperma
Arabis sparsiflora
Barbarea orthoceras
Barbarea vulgaris
Brassica nigra
Brassica rapa
Cardamine californica
Descurainia pinnata
Sinapis arvensis
Sisymbrium officinale
Streptanthus tortuosus
Thysanocarpus curvipes

Pyle has also observed A. sara using Cardamine penduliflora.

Bittercress is very common and I'm sure some of my seeds have spit across the Columbia and on to your patio.

The Orangetip should be on the wing any week now.

Larry_G,
Bittercress is a Cardamine? Western Orangetip(Anthocharis s. sara form Reakertti)& N Duskywing were feeding only on this blue society garlic like flower on long thread stalk found only on sloping sunny open woods mountain sides.Very weary lepidopt. What is it Larry? Saw very few milkweed (A. speciosa) too. MOst at Beekman House Native plant exhibit at " "entrance in Jacksonville. Spotted a recycling pool with fish & tadpoles. 2 weeks ago in medford, OR I observed 3 fresh Western Orangetips & some A. s.sara form Julia. I'm growing common Cabbage & ornamental cabbage. Should of planted radishes this year.