Other forms: grists
When grain like wheat or oats is ground into flour, it's called grist. Maize or corn that's made into coarse grist is called "grits." Grits. Yum.
When grain is prepared for grinding, the grist is separated from the chaff, or the thick seed covering. You may have heard the saying, "It's all grist for the mill." What that basically means is that anything at all can be useful or profitable—or that someone can put a positive spin on anything. It comes from the idea that any grain at all is useful to a miller who grinds it into flour.