I know there are dozens of great buckwheats, but surely the queen will always be E. ovalifolium? This lil' sucker is everywhere in the Intermountain West--especially common and beautiful practically anywhere in Idaho, the Sierra-Cascade crest and even the San Rafael Swell, the latter being the source for the plants I grew several years in my dryland garden shown below. My only complaint about this marvellous plant is that it does not persist for me in the dry garden: it will grow lustily and bloom its head off--and then die. In my irrigated rock garden, however, they live much longer. What kind of longevity do you have?