Ask Mr. Smarty Plants

The short answer is no, picking flowers from these plants will not kill them, nor keep them from reproducing.  A longer addendum to that answer is that the flowers are all so tiny and mostly inconspicuous that we can't think why anyone would want a flower badly enough to get down on their hands and knees to pick one. They mostly have very short stalks which wouldn't lend them to being placed  in a vase. Apparently all of the species we have listed below are native to your area, in and around Sonoma CA, so you must have ideal growing conditions for them in that vicinity. The three plants you asked about, Trillium,  Blue Dick and Fawn lily, are all members of the Liliaceae family, propagated by both corms and seeds. In order to narrow down the list, we chose only members of those genera native to California. You can follow each plant link to our webpage on that plant to learn its growing conditions, etc.

Trilliums - 39 native to North America, 3 to California

Trillium chloropetalum (Giant wakerobin)

Trillium ovatum (Pacific trillium)

Trillium rivale (Brook wakerobin)

Blue Dick:

Dichelostemma capitatum ssp. pauciflorum (Little bluedicks)- according to this USDA Plant Profile Map this only grows natively to inland Southern California

Fawn Lily - 11 native to North America, 5 to California

Erythronium californicum (California fawnlily)

Erythronium grandiflorum (Yellow avalanche-lily)

Erythronium oregonum (Giant white fawn-lily)

Erythronium purpurascens (Purple fawnlily)

Erythronium revolutum (Bog fawn-lily)

From our webpage on Trillium chloropetalum (Giant wakerobin), here are Propagation Instructions, which are pretty standard for all members of this family:

"Description: Rhizome division or seed. Seeds do best when planted outdoors soon after fruits have ripened. Plant seeds 1/4 in. deep in a moist, humusy location. Seedlings take many years to bloom. Divide rhizomes in fall."

Translation: If you pick a flower, it will make no seeds for that particular plant, but the corms (rhizome division) will still be there to propagate the plant, which takes a long time in any case.