Grains of domesticated grasses (Poaceae) have long been a global food source and constitute the bulk of calories in the human diet. While most contemporary grass domesticates consumed by humans are annual plants, there are over 7000 perennial grass species that remain largely unexplored for domestication purposes. Documenting ethnobotanical uses of wild perennial grasses could aid in the evaluation of candidate species for de novo crop development. In this study, we 1) provide an ethnobotanical survey of the perennial grass genus Elymus; and 2) investigate floret size variation in Elymus species used by people. We identified at least 21 taxa with recorded nutritional, medicinal, and/or material uses and at least 25 different indigenous communities associated with a use. The most common ethnobotanical use of Elymus in this survey is as forage, though at least 12 species are consumed by humans. Elymus species used for food warrant pre-breeding and future analyses to assess potential utility in perennial agricultural systems. We found average floret area does not differ significantly across geographic regions and among documented ethnobotanical uses, with the exception of species used for medicine in North America. A variety of Elymus species show promise for continued human use, and standing morphological variation in the genus should be further explored.