California currently allows the sale of cannabis to both registered medical cannabis patients as well as adult-use cannabis consumers.
To shop, California requires medical patients to be at least 18 years of age with a valid California Medical Marijuana card and valid government issued photo ID. They do not offer reciprocity, so out-of-state medical patients must shop as adult-use.
Adult-use cannabis consumers must be 21 years of age with a valid government issued photo ID (in-state and out-of-state).
See also:
What information is required to shop in California?