What plants did primitive man grow?

None. It was from the moment of the inception of agriculture (in some regions of cattle breeding) that the transition from primitive relations to more developed ones took place.

By appropriating the gifts of nature (by hunting or collecting edible wild plants), people depleted their reserves very quickly. Starting to grow food, they made the transition to a developed society and the first states. The surplus of food was also the first commodity that communities of ancient people exchanged among themselves.