Summer snowflakes are very easy to grow in Southern California. They return every year, the bulbs multiply reliably in my garden and are hardy to USDA zone 4. Read more at Wikipedia and order next year at Easy to Grow Bulbs . (Too late to plant for SoCal).

Snow-drops

The Snow-drop, 
Winter’s timid child,
Awakes to life, 
Bedew’d with tears.

—Mary Robinson

Though these are not actually snowdrops, they’re my SoCal garden equivalent. My “winter snowflakes” are just starting to bloom now and have delighted many in my street-side garden and in bouquets for twenty years.

Description at Easy to Grow Bulbs: White bell flowers festooned with green oval accents. Reliable blooms - winter hardy and heat tolerant in nearly all climates. Thrive in full sun to partial shade. Pretty spring bloomers. Excellent mixers with late season tulips. Lovely fragrance. Deer and rabbit resistant.