Lentils

Boyd’s Bible Dictionary:

(little lens). A podded food plant, like the pea or bean (Gen. 25:34; 2 Sam. 17:28).

Concise Bible Dictionary:

Red Lentils
The small seeds of different kinds of vetch used for food. The Arabic name is Adas. When ground, the meal can be made into a palatable red pottage (Gen. 25:34; 2 Sam. 23:11).
Lentils formed part of the provisions furnished to David and his followers on the revolt of Absalom (2 Sam. 17:28). They were also used in a time of scarcity, and among the poor, as an ingredient of their bread (Ezek. 4:9). The Ervum lens is cultivated in Palestine.