Maybe a Mentha
I found highly branched plants this morning that were about 4 feet tall. They had leaves to 1 inch wide by 3 inches long on 0.6 inch long petioles that were smooth. Stems were also mostly smooth. The flowers were just developing from leaf axils toward the top of the plants as shown. I did not find any hairs in the inflorescence. Although the plants had a strong aroma of spearmint when bruised, they did not key to any of the local species in this area. IÃ¢ÂÂm sure that the species would be easier to determine if the plants were mature. However, this field may be mowed before that event occurs. Is this M. aquatica? It doesnÃ¢ÂÂt seem like the flowers will be clustered tightly enough around the stem for that species. I guess I should mention that the lower peduncle in the second photo is about 0.75 inch long (for perspective).