Grasses were a diverse group of plants from Earth, which included the grains. Grass-like plants were also found on many other planets. Grass that was cut, dried and used for animal feed was called hay.
Malcolm Reed was allergic to tropical grasses. (ENT: "Silent Enemy")
The Xyrillians grew grass on the floors of their starships. Charles Tucker III once noted the gasses they emitted helped the Xyrillians metabolism, and smelled like a "freshly mowed lawn." (ENT: "Unexpected")