Fragrant fritillary is endemic to the San Francisco Bay region of California, preferring “open hilly grasslands at altitudes less than 200 meters (650 ft.) in elevation”. It is perhaps unsurprising that its preferred habitat conflicts with urban development pressures and agriculture; as such, it has been proposed as a candidate for listing as a federally-endangered species in the USA.
It is an exception to most other species in the genus in that it is sweetly-scented, hence the common name. Most species of Fritillaria have a fetid floral odour, and are pollinated by wasps or flies. Known pollinators for Fritillaria liliacea include the yellow-faced bumblebee (Bombus vosnesenskii) and long-horned bees (Eucera spp.). For more on pollination in Fritillaria (from the source of my information), see Pollinators via the marvelous Fritillaria Icones site (“a photographic botanical database to help with the identification, research and conservation of Fritillaria“). The site also happens to have one of the best pages on the discovery and history of Fritillaria liliacea.
If you’d like to see and read more about fritillaries, I’ve updated the dozen or so previous BPotD entries on species of Fritillaria. You can most easily find these by clicking on the Liliaceae tag.