I can't find any California laws that are about not taking school lunches at home. So, I see no problem with taking a school lunch at home.
I used to bring packets of salt and pepper during Middle School, but I gave up going to the cafeteria in High School and now walk into town for food from some place or another
I remember bringing packets of ketchup back in middle school. And then I would make ketchup bombs out of it and then throw it into the ground.