Shell remains from two mollusk species Gonidea angulata and Margaritifera falcata are commonly found in archaeological sites along the western Snake River. There have been, however, no attempts to assess their nutritional value and dietary role. To further understand the role of mussels within prehistoric diets, the nutritional values of these species were compared with the values of other resources commonly found in riverine settings in southwest Idaho. Though the caloric value of mussels is relatively insignificant, these species do contain important levels of iron, carbohydrates, calcium, vitamin A, and ascorbic acid. A discussion of the life history of these species provides for consideration of possible seasonal use of mussels during the late winter and spring as a valuable source of nutrition during a time when other resources were scarce. Of particular note is the increase in protein, glycogen, and sugars during this time as well as the presence of polyamine compounds which have implications for use of mussels for their antioxidant and anti-inflammatory characteristics or as a seasonal appetite suppressant.