Twice a year, anyone can fish without a license in California. It’s an easy and hassle-free way to give fishing a try. This year, the days are June 7 and Sept 27.
From the CA Dept of Fish and Game web site:
The Department of Fish and Game offers two Free Fishing Days each year. On these days, you can fish without having to buy a sport fishing license. Free Fishing Days provide a great, low-cost way to give fishing a try. Some Department offices offer a Fishing in the City program where you can go fishing in the middle of major metropolitan areas, perhaps just a few blocks from your home. Fishing in the City and free fishing day clinics are designed to educate people just like you about fish habits, proven methods of catching fish, and tackle you’ll need. You can even learn how to clean and prepare your catch so you can enjoy it for dinner that night.
More at the CA Department of Fish & Game.