Romulea rosea growing among other leafy plants.
A flash of pink is nestled at ground level, surrounded by long grass-like leaves. This is rosy sandcrocus, or Romulea rosea, a South African native that is in the iris family. And though superficially it doesn’t look at all like an iris, there are certain similarities if you know what to look for.
Rosy sandcrocus has six pointed pink petals, and long linear leaves with parallel veins running all the way to the end. Beneath each flower is a slight bulge in the stem, which is actually the ovary where seeds will develop (many flowers have “superior” ovaries, which means they are snuggled in among the petals rather than below them. The “inferior” ovary is a characteristic of the iris family). Six petals, and leaves as described above, are also key characteristics of Iridaceae.
The rosy sandcrocus was first collected in Marin in 1979, and probably was accidentally brought to the area in a load of clover seed from Australia, according to the Marin Flora. In places, it takes over entire areas–looking a lot like a field of grass, except for when the pink flowers are blooming. Overall it isn’t abundant in California, and the places you do find it tend to be weedy, disturbed areas–often with dry, sandy, or compacted soils.
This little perennial sprouts from a pale, bulb-like corm. 
Flowers Of Marin 