grain: the harvested cereal crop, chiefly wheat and barley, that a land yields for food
This is the everyday word for grain as a harvested crop. It is a collective term, not the name of a single plant: it gathers up the cereal yield of the fields, mainly wheat and barley, considered as food. English Bibles usually render it "grain" or, in older versions, "corn."
Almost every time it appears, it stands beside two companions: new wine and fresh oil. That trio (grain, wine, and oil) is the shorthand of the Hebrew Bible for the staple produce of the land, and so for prosperity and God's blessing on a farming people. To speak of grain, then, is usually to speak less about botany than about provision: what the ground gives, what fills the storehouse, what is tithed and offered.
Because it names the yield itself, the word turns up wherever the harvest is at stake: in blessings and curses over the land, in tithes and firstfruits brought to the temple, and in scenes of famine when there is none. When the prophet Hosea says the people never grasped that it was the LORD who gave them the grain, the wine, and the oil, the point rides on this word: the harvest is a gift, not something the local fertility gods supplied.