People in Ethiopia still use oily seeds from trees and shrubs that are either wild or tolerated in gardens, to grease their ceramic griddle before baking bread. Many significant African food sources have not been domesticated but still play a major role in subsistence. Also, root and tube crops such as yams are especially unlikely to preserve. Same time period and later, but these sites difficult to date. Nile Valley in Egypt.
Charred baby feces an excellent source of subsistence data.
Interestingly enough, Cyperus rotundata never was domesticated. But mobility is the rule. This probably made life very tough and also did not favor accumulation of archaeological deposits. At that time, the Sahara was not a desert, but fully habitable, with lakes, etc. Otherwise you may get confused.