Take a look at this article about Milkweed. Did you know it is the only plant where Monarch Butterflies lay their eggs? At Cerritos College we have some on the west side of the library. Maybe we will see more Monarchs this spring.
Locally I know the Shipley Nature Center in Huntington Beach sells milkweed, and there are native plant nurseries in Claremont and San Juan Capistrano that do as well. The Rancho Santa Ana Botanical Gardens in Claremont is a great place to wander around and enjoy native plants. They have a wonderful native plant nursery. The Tree of Life Nursery on the Ortega Highway outside of San Juan Capistrano is right next to Caspers Wilderness Park which is a huge park with great hiking trails and camping.
Click here to go to the article about milkweed and Monarchs.