Bible Dictionary · G
Grain
Used, in Amos 9:9, of a small stone or kernel; in Matt 13:31, of an individual seed of mustard; in John 12:24, John 12:1 Cor. 15:37, of wheat. The Hebrews sowed only wheat, barley, and spelt; rye and oats are not mentioned in Scripture.
From Easton’s Bible Dictionary (1897), by Matthew George Easton.