what is the law regarding selling seeds in california?

I understand that shipping them out of state is federally illegal. what about selling hand to hand within my own legal state?
is there a license required?

Unless you're just growing six plants for personal use you need a license to do anything. You'll need a cultivation license just like nurseries that sell clones. Seeds fall under the category of products used for the cultivation and propagation of marijuana.

Check your laws. Read the wording.