Standard field equipment, a small cooler with stuff to eat and plenty of water. A chair to sit in a hat and sunglasses.

My flight box has a field charger, extra props and glow plugs (OS A3's, OS # 8's and OS "F" plugs), my "Stooge" (plane hold back), a Buddy Box and cord just in case, extra clevises, wheel collars, fuel tubing, nuts and bolts, packing tape, most any little thing that someone might need to help them keep flying.
Dennis-