In Michigan, California Poppy is grown as a self-seeding annual. The entire plant (roots, leaves, and flowers) can be harvested in late summer when the plant is flowering. Preserve the fresh, finely chopped roots in 40% alcohol to make a tincture that will last for years. Flowers and leaves can be carefully dried to make tea. Use one or two teaspoons of dried herb in eight ounces hot water and steep for 45 minutes. To collect seeds, watch for the plants to form long, thin seed pods and wait until the pods begin to turn brown and dry. Collect intact pods into a brown paper bag and allow them to dry. The pods may burst open on their own, or you can gently roll them between your fingers to extract the small, black, round seeds.