I'm 16 and I have been wanting to get my septum pierced. Do I need to bring a sort of ID to confirm my age or is my parent being there/there consent enough? I have a California ID from when I was younger(expired),and I can bring a school ID as well.

Your parent being there is consent enough. Make sure they bring a long their picture ID. Piercing walkin hours are 12 to 5:30pm daily.

According to CA law, you're fine so long as "the body piercing is performed in the presence of, or as directed by a notarized writing by, the person’s parent or guardian." I would assume that ID is simply to prove that they're in fact your parent, instead of some random person you paid $20 to help you get a piercing.