These are the flowers of Giant Bur-Reed (Sparganium eurycarpum), a native perennial found in freshwater wetlands on Bodega Head. It's hard to tell from these pictures, but this is a large plant with cattail-like leaves growing up to 2.5 meters tall (the leaves are keeled at the base).
The large flowers below are females, with long white stigmas. (In the photo below, there are male flowers above and to the right of the females, but they're not open yet.)
The male flowers are located above the females. They open at different times, with the lower flowers maturing before the upper flowers. In the next photo, the lowest flowers are wide open, the middle flowers are starting to open, and the highest flowers aren't open yet.
For some reason, this plant always reminds me of Dr. Suess:
Follow female flowers
And male flowers create zigzag towers
I could look at these flowers
for hours and hours
even while it showers!