Hi Nicole,
Thanks for visiting the Disney Parks Moms Panel!
Park rules prohibit suitcases, coolers or backpacks (with or without wheels) larger than 24" long x 15" wide x 18" high inside the Parks at the Disneyland Resort.
With that said, if you each bring a small cooler (something big enough to store a six-pack), you're generally allowed to bring light food and snack items that don't require heating.
I personally like to pack juice boxes, sliced fruit, pretzels and bottled water for my sons.
I've also seen guests pack more elaborate food items like sandwiches and small salads.
Keep in mind you can store your coolers inside a
locker rental and enjoy food either inside the Parks or in a very nice little
picnic area located outside the Disneyland Main Entrance turnstiles.
I hope this helps!
Have a Magical time!
-Anabel M.