I do not know how correct this is but:
My grandfather came to the United States in 1901 from Germany.
He introduced us to several terms. One of them was Jitney Box. It was to become to us a term that meant picnic box for the car.
We would pile into the Jitney Bus (an old car commonly called a woody that I think meant a transport vehicle in his language) it was somewhat like a station wagon with wood on the exterior (probably useless information). Anyway he had built a type of picnic box out of wood. It had compartments for forks, knives, etc. that would hold the day's food. He always refered to this picnic box as a jitney box. It was handed down to me so if you want plans on how to build one you can contact me at dsmith3@dot.state.tx.us
My son got me here to respond to you and I will probably never find this site again.