Buckwheat is actually a member of the rhubarb family.
Nutritionally buckwheat resembles wheat. Rich in iron, B vitamins and calcium, buckwheat flour is also gluten free and can be used like a grain. Made into a flour, it has a strong grainy flavour and is best used in pancakes, waffles, noodles, breads and cakes.
Best when combined with wheat and/or rye flour.
People with wheat allergies can eat buckwheat.
For cooking/baking use buckwheat groats (1). Buckwheat husks (2) can be used to fill pillows. The husks are only available for a short time (roughly around Feb to Apr).