Butnij (river mint) in medieval times was called butanaj nahri (river mint), described as a wild variety of mint. In Iraq today, butnij is always used dried. It is crushed and sprinkled over the traditional fava/broad bean dish tashreeb bagilla (boiled beans with bread sopped in its broth, recipe) before serving it, as this is believed to help with the gasiness which the beans usually cause.
In the United States, I have seen it growing along creeks and riverbanks. Folklore has it that, if you want to drive away snakes, you should grow this herb around the house. Indeed, so legendary is the enmity between the snake and this herb that if the chemistry between two persons does not work at all, people would say they are mithil il-hayya wi’l-butnij (like butnij and the snake). If butnij is hard to find, regular mint can be substituted. Also see MINT.