At the Rebild Festival it is possible to buy food, drinks and snacks. You can find food stands before the entrance and below the hills. The theme of the food stands will of course be American.
You are welcome to bring your own picnic basket. Rold Storkro has put together a nice picnic basket that you can pre-order already now. NB. it has to be picked up before 11 AM on the 4th of July.