Are California king snakes poisonous

In my experience - yes. I've been keeping/breeding reptiles for over 25 years, nad have found them an Excellent 'beginner snake' - since they seldom (if ever) show any aggression towards being handled.

What I would say, though, is before you get your first snake, please do some research on the particular species you're interested in. That way, you'll have at least some basic knowledge to help you take care of your new reptile successfully. I rescue many reptiles each year from owners who didn't know how to care for their animals.