Every year a plant reseeds around our grain bins. My first guess would be that it's related to buckwheat, except that it has opposing stems. It grows to a height of around 18 inches. Its flowers appear in terminal clusters and are at first magenta in color, turning to light green as they mature. Most contain three tiny seedpods, grenade-shaped with four ridges running vertically. The leaves are a deep green and arrow-shaped and grow from the stem junctures.