Hi Stacey!
You can certainly bring your own food into the park and I do this all of the time because I have special dietary needs. I like to bring food that is small, doesn't require refrigeration and is fairly healthy. I usually bring my snacks in a small backpack that I use to carry all of my park essentials (ponchos, refillable water bottles, bandaids, sunscreen, a hat).
Backpacks are permitted, but coolers and backpacks larger than 24" long X 15" wide X 18" height, are not allowed.
I like to buy small bags of individually packaged nuts or trail mix. I also like to bring protein bars for those times when I'm hungry and waiting in line. If you are looking to bring more of a "meal" consider items that are easily portable and don't require refrigeration. Packs of tuna, peanut butter and jelly sandwiches, apples and crackers are good options.
Don't miss out on some of Disney's awesome food when you are there. No trip is complete without a Dole Whip from
Aloha Isle, a Mickey Mouse pretzel from
Lunching Pad and a Mickey Mouse ice cream.
Magically,
Stacy