This is Corylus cornuta californica, also known as Western Beaked Hazel, and California Hazelnut. This shrub has both male and female flowers and it pollinates itself through the wind. The California Hazelnut plant is happy in full shade or full sun. The seeds, or nuts, can be eaten raw or cooked, fresh or preserved. Some people use the seeds to make an oil which is edible. Fiber from the inner bark can be used to make cord or paper. Corylus cornuta californica is a larval host plant for the Half-white Carpet Moth. USDA Hardiness Zones 4 to 9