Some of the items you can make homemade to bring along, Mini muffin, Rice Krispy Treats, homemade trail mix, mini brownie bites or cookies. You just need to store in an air tight container. If you have a Disney ears cookie cutter it works great, and makes them special
I have friend that use's Garden Grocer they prefer this method rather that shipping a box. This way they can get some items like fresh fruit and cream cheese for bagels and other items for the baby. And adult beverages for the evening without breaking the bank.
When DD was little she was a picky eater... so I would bring "her bread" for toast in the mornings, I think all the food courts have a toaster, also I would bring her cereal and just buy a carton of milk. Also when DH and I had both girls we loved to stay at CBR, We would use the courtyard area in the mornings for breakfast, I would get breakfast started outside while DH was in the shower and getting dressed, then we would switch off, I would hit the shower, get ready, check the bags for the day, Then change the girls into their park outfits for the day, and head out. This worked really well for us, and saved money for breakfast, and the kids would get some food in them.
Also a soft sided cooler is great for the parks, we took in the gel freezer pack thingy, to keep thing cool - along with capri suns, juicy juice, bottle water, and a must have coke for mom... grapes, or apples, and string cheese. Then in a smaller air tight container crackers, chips or dry cereal. I preferred a hard container to keep things from getting smooshed.
You can share meals, head over to all ears, they have current price and menus so you can look ahead to see what you can share ahead of time.
I have another friend that gets a double cheese burger meal and a extra bun and splits it up patty so that each kid gets a whole burger, they choose some where were a toppings bar is, so that each kid can put what they want on their burger, then she puts all the fries together so that no-one can say he got more..
Have a wonderful time.