Buckwheat article on wikipedia here says it is related to sorrels, not wheat.
Most people only know about it from buckwheat pancakes or in some cuisines, eating Blinz or groats.
And is used in Asia e.g. soba noodles.
it was often used to counteract the vitamin B deficiencies from eating only white rice.
and since buckwheat is gluten free, it can be used by those on a gluten free diet.
but if you eat too many, you could develop a light sensitivity rash.