...........California natives are in bold type

Ajuga reptans
evergreen,likes regular water, but can be amazingly drought tolerant. grows in sun or shade. There are many different varieties of varying vigor, leaf size, and foliage color. Spike flower in spring is usualy a very nice blue.
evergreen and perennial varieties. Usually quite drought tolerant and grow best in full sun. Foliage is usually a shade of grey or silver, although there are green ones, such as the herb Tarragon. Artemesia pycnocephala ("Sandhill Sage") and Artemesia californica are low growing natives.
Baccharis pilularis
("dwarf coyote bush") Evergreen, very drought tolerant, full sun. This California native is extremely tough, can be attractive if kept sheared. Grows very fast, the flip side of that is that it can be somewhat short lived.
Cerastium tomentosum
("Snow in Summer") evergreen, can handle a lot or little water, full sun. Foliage is ground hugging and silver, covered with white flowers in early summer, vigorous and possibly invasive in some sites.
Ceratostigma plumbagoides
Perennial, can take a lot or little water, full sun to partial shade. Foliage has a nice reddish cast when new, gets very red in fall. Flowers are absolutely stunning intense blue. Vigorous and can be invasive.
Erigeron karvinskianus
Evergreen, can take a lot or little water, full sun best. Flowers almost all year round with little white daisy type flowers. There is a pink blush on the back of the petals, more pronounced in one variety. Spreads easily by seed, but not really invasive
Hypericum calycinum
Evergreen to semi deciduous, very drought tolerant when established, full sun to partial shade. Golden flowers on dull green foliage. Can be very invasive.
('Oregon Grape") Evergreen native for shady areas. Several kinds, from low groundcover types to nice big shrubs. Clusters of small fuzzy yellow flowers followed by dark edible, but bland berries. The leaves are glossy green, sometimes with a nice bronzy blush, usually prickly.
Evergreen, best with regular water, but can get by on very little. Grow in full sun to partial shade. Quite a few different varieties with various heights, foliage and flower color, but most are some shade of lavander blue or white.
Evergreen, do well with regular water but are drought tolerant. Full sun for some, partial shade will work for some of the yelow green forms. The Oreganos that work well as ground covers are the Origanum lavigatum and Origanum vulgare types - tough, making evergreen, low, spreading mats of foliage that the flower stalks arise from.
Ornamental Grasses
Many different kinds, some evergreen, some perennial of varying heights and shade and drought tolerance
("African Daisy") Usually evergreen, drought tolerant and best in full sun. Somewhat gangly, but cheerful. Flowers are usually some combination of purples and white.
Evergreen, drought tolerant, usually will not tolerate regular watering, full sun. Tough, nice deep green foliage, nice blue flowers in early spring. For gound cover make sure you select a low growing variety
Evergreen, drought tolerant, full sun to shade depending on variety. Salvia sonomensis is the native sage found growing under oaks or on north facing slopes along with Festuca californica. There are several other native Salvias or hybrids of them, that will do well in sunny areas.
Sollya heterophylla
Evergreen, moderate water with good drainage, partial shade. A sprawling plant with small glossy leaves and nice blue flowers. When happy it is quite lovely, but seems to struggle from too much winter cold and is often particularly susceptible to aphids
("Lambs Ears")Evergreen, regular to little water, full sun. Often used in front of flower and shrub beds, very silver, felty foliage. Spreads willingly, sometimes a bit too willing. A couple choice varieties either have nicer flowers or flower hardly at all, both an improvement on the standard "lamb's ears".
Evergreen, all seem to be drought tolerant, some are more tolerant than others of bad drainage or regular water. Full sun to partial shade. Teucrium Chamaedrys 'Compactum' or 'Prostratum', which is the "flattened" version of the classic Germander is great for ful sun to some shade and little to a lot of water. It is dark green and has nice soft magenta flowers. Teucrium cussonii is beautiful with dusty grey foliage and a soft rosy lavender bloom over a long season, but must have excellent drainage and seems to be very drought tolerant.
Evergreen, regular to little water, full sun. You can make a tapestry of these sweet, tough little plants. Some seem to rarely bloom, but the ones that do can make a dazzling carpet of mauve, hot pink or white in spring to early summer.