From your link:
they let me bring in an 8x8x12 cooler with food last year. Water bottles had to be sealed. No soda. We brought in chips and sandwiches for the 4 of us (wife and two young kids) and a bag of peanuts.
And you have to bring your own food/drinks to the backfields...
16x16x8 single compartment soft sided cooler is allowed. Water, milk, (sealed) and “medically necessary food” are allowed.
"Food – Guests may bring food into the CenturyLink Sports Complex required for legitimate medical purposes only."
EDIT: Sorry, missed your correction.