IMG_1377 on Flickr.

Beach Evening Primrose (Camissonia cheiranthifolia)
This lovely California native spreads along the ground and grows in flat lacey patterns on sand dunes and beaches. It spreads about 3 feet wide. Its small regularly spaced gray-green leaves are enhanced by silky yellow flowers which brighten up the Sand Dunes trail in the spring and summer. - BolsaChicaLandTrust.org

From one of Angus and I’s walks at Bolsa Chica, back in October. The sun had already gone down and this flower was in the process of closing up for the the night.