Another veteran here letting you and everyone else know there is ABSOLUTELY NO PROBLEM with taking as much food as you want into the parks. As you read earlier, no "hard-sided" coolers, no glass (except baby food jars), etc., but everything else is fair game. People who bring food into the parks aren't getting away with anything. Believe me, the security guards root through the bags pretty well (and NOT in a rude manner), and they see everything. On two different days we brought lunch for the 6 of us, plus snacks and bottled water, and on all the other days we brought bottled water, snacks and a couple emergency PB&Js.
Mangia!