File:Flag of California.png

Unlawful Uses California State Flag
While the design on the California state flag is in the public domain [having been first published at least as early as 1911 -- see http://en.wikipedia.org/wiki/California_state_flag ], it is UNLAWFUL under California law:

1. to solicit information, 2. to solicit the purchase of or payment for a product or service, or 3. to solicit the contribution of funds or membership fees by using the design on the California state flag and 4. to use that design in any way that would deceive an ordinary reasonable person into believing that its use is authorized by the State of California.

See CA Bus. & Prof. Code § 17533.6(a) and Penal Code §§472 and 538g(b).