the.com/buckwheat groat

means The hulled, triangular seed of the buckwheat plant, cooked and eaten like a grain even though it's botanically a fruit seed related to rhubarb and sorrel.

from 'Groat' traces back to Middle English/Dutch 'grote' or Old English roots meaning a broken or hulled grain fragment — the same word family that gives us 'grits' and 'groats' for oats and barley. 'Buckwheat' is the odd one: it comes from Dutch 'boekweit,' literally 'beech wheat,' because the plant's seeds are small, dark, and three-cornered, resembling the nuts of the beech tree. So the name is a double disguise — 'wheat' it isn't, and 'beech' it also isn't, just borrowed shapes from two different plants to describe a third thing that's really a fruit seed in a cereal's clothing.