Well-preserved plant remains recovered from archaeological deposits at the Paisley Five-Mile Point Caves and Little Steamboat Point-1 Rockshelter in southcentral Oregon provided a rare opportunity to study ancient plant resources used by northern Great Basin indigenous groups and their ancestors with Western Stemmed technologies. Macrobotanical analysis of cultural features and vertical columns spanning the Terminal Pleistocene and Holocene epochs in the rockshelter repositories yielded thousands of seeds and charcoal fragments that can be attributed to human activities. Data generated in this analysis have provided evidence of paleoenvironments along with the diets and social behaviors of people visiting northern Great Basin rockshelters as a stopover on their seasonal subsistence rounds. The preponderance of upland shrubs and herbs in the assemblages at both archaeological sites indicates vegetation in the immediate vicinity of the rockshelters was fairly stable over the past 14,000 years. The macrobotanical data complemented local and regional pollen analyses to refine the paleoecological proxy data and address uncertainties regarding the proximity of wetland plants and pine (Pinus sp.) to the rockshelters in the past. Samples originating from Younger Dryas deposits at the Paisley Caves and Late Holocene deposits at the Paisley Caves and LSP-1 Rockshelter suggest increased visitation frequency in these periods. The diverse assemblage of cultural plant remains during these times also indicate a broad diet breadth for Great Basin foragers, which included small seeds, nuts and berries, and root vegetables. The presence of an earth oven feature dating to the Terminal Pleistocene/Early Holocene (TP/EH) in Paisley Cave 5 further demonstrates sophisticated traditional knowledge of plant foods and cooking techniques as early as 12,000 cal BP. This study also generated data chronicling the deep historical roots of traditionally valued economic plant foods. Cheno-ams, grasses (Poaceae), and tansymustards (Descurainia sp.) are well-represented in fire hearths at the Paisley Caves and LSP-1 Rockshelter through time. Analysis of a bushytailed woodrat (Neotoma cinerea) nest in deposits dating to the TP/EH demonstrates rodents living in the Paisley Caves routinely scavenged resources from cultural activity areas, and raised questions about whether people recognized the woodrats’ nests as a reliable resource of cached edible seeds.