What did the spies carry back on a pole between two men?

Answer: A cluster of grapes

In the Valley of Eshcol the spies cut a branch with a single cluster of grapes and carried it on a pole between two men.

“When they came to the Valley of Eshcol, they cut down a branch with a single cluster of grapes, which they carried on a pole between two men. They also took some pomegranates and figs.”— Numbers 13:23 (BSB)