Anigozanthos spKangaroo Paws. Probably a cultivars of Anigozanthus flavidus. Kangaroo paws, a Western Australia native, flowers nearly the year around in the San Francisco Bay Area. Photographed in a private garden in Berkeley, CA
A Yellow Dayflower, native to sub-saharan Africa. The leaves are edible and the plant has several applications in folk medicine. Photo from the Liparamba area of Tanzania.
Tribonanthes purpurea This is a tiny flannel flower which grows in moss on granite rocks. It is listed as a Threatened plant and grows in only a few locations. The flower is about 1cm tall, the leaves growing to 3-4cm. It is a very hard plant to locate and find even when you know where it is. More photos in first comment
Native to Central America and Mexico, this species is now pantropical due to its use as a ground cover. Names include Inch Plant, Wandering Jew and Amor de Hombre.
Tribonanthes brachypetalaThis is a plant which over the years, I thought was disfigured, because it didn't have showy petals. This is how it grows with short yellow petals and long reflexed bracts. It is quite attractive if you stop and look.