Non-native and Invasive Species
According to the National Park Service, of over 900 species of vascular plants in the Point Reyes National  Seashore, 292 are not native.
European sea rocket (Cakile maritima) is an invasive found on coastal dunes in California (>).  A couple dozen of these plants were growing in the sand in a small cluster on Wildcat Beach, but they did not seem widespread.
Brass buttons, golden buttons or buttonweed (Cotula coronopifolia), native to southern Africa. 
Ice plant (Carpobrotus) >.