Add your pictures and correct ID. This will be a future Sticky. Barnyardgrass Echinochloa crus-galli, Wild millets in this area can also fall under E. colona, E. muricata and E. walteri. Excellent waterfowl food producing a large seed favored by mallards. Stem is flat at the base. See photo. Japanese millet is domesticated from barnyardgrass. Can easily grow to 3' -4' tall but have seen it pushing 6' in rare cases. Capable of growing on higher/dryer sites.