This is the robust, horticulturally distinct, variant of multiscapöideum which is found in a small area of Serpentine cliffs and screes around Pulga Bridge in California.
It makes silvery patterned leaves below a large, white flower with a yellow glow in the throat. This yellow zone can be marked with an additional brown ring or zone or even a replacement diffuse brown ring in some plants, as the species (or forma - depending on your botanical blinkers), like many, is a little variable.
Seed-raised from a Wayne Roderick collection made many years ago. An excellent garden species flowering well and increasing nicely with several scapes to each pair of leaves.