Recent excavations at three prehistoric sites in eastern Idaho recovered a moderate amount of culturally-introduced macrobotanical remains, including mountain ball and prickly pear cactus, goosefoot, sunflower, and tobacco, all of which came from contexts dating between 1500 B.C. and A.D. 1000. Within the greater region, cactus, goosefoot, and sunflower were first used by people between ca. 11,000 and 8500 B.C., whereas the archaeobotanical record for tobacco dates back to 10,300 B.C. The Birch Creek Valley data set allows us to explore aspects of local site function and settlement practices, as well as the temporal range and ubiquity of the above-listed taxa within the northern Intermountain West and adjacent portions of the central Rocky Mountains.