Actually, Buckwheat is a very interesting and nice crop to eat. First of all, it is very reach in iron, so it is a good natural source for that mineral. Secondly, it will digest rather slowly, so it will give you more energy for longer.
One fun fact from the past. In the really old times in Tsar Russia (buckwheat is very popular there), they would measure how energy efficient are different foods. Their index was - after eating a plate of this food, how much field work can a man do. With buckwheat they were getting the most work done, because as I mentioned above, it gives a shit load of energy for a very long time, not in a spike.