Disney won't ship food themselves. No guarantee how it will arrive, when it arrives, etc so it's not worth it. If you bring/find a box, you can go to the front desk/concierge at a resort, and they can ship things home via FedEx/UPS. May just take a white lie if they ask "Does this contain perishable items?" You will be charged the shipping rate via the FedEx/UPS calculator, plus a handling fee by WDW. Sometimes this is cheaper than having WDW ship things home from the store as those shipping rates are decided by cost and not size/weight, but WDW takes no responsibility for the package if something happens to it.