Yellow Glacier Lily, Erythronium grandiflorum

Also known as Fawn Lily, this beautiful flower was found in abundance on Kamiak Butte.

Dame's Rocket, Hesperis matronalis

Originally from Europe, this garden escapee has very fragrant flowers and has established itself along roadside ditches in the Northwest.

Western Meadowrue, Thalictrum occidentale

Male and female flowers are on different plants.  Male plants, shown below, were growing at Moulton Falls County Park in SW Washington.

2015 update:
I found some female plants growing on Bells Mountain in SW Washington.  It was a foggy morning and tiny water droplets were on the flowers.

Hooker's Fairybell, Disporum hookeri

This native member of the Lily family has berries that appear later in the Summer that taste somewhat like watermelon.

Cusick's shooting-star, Dodecatheon cusickii

This striking flower was found near the summit of Kamiak Butte, north of Pullman, WA

Pacific Bleeding Heart, Dicentra formosa

This common native perennial, also known as 'dutchman's breeches', is an old-fashioned favorite.

Western Saxifrage, Saxifraga occidentalis

I Found this native perennial growing out of a moist rock outcrop on the East Fork of the Lewis River.