The seed bank represents the future trajectory of plant communities following disturbance and is vital to their regeneration. Worldwide, grassland seed banks have been well studied. However, there are no examinations of the seed bank for the Pacific Northwest Bunchgrass Prairie system found in the Pacific Northwest of the United States. This absence may arise from the limited amount of intact grasslands in this type following decades of agricultural development and cultivation. In this study, we examined the seed bank from grasslands sites along an early successional gradient to evaluate how they relate to above ground vegetation, successional stage, and historical cultivation. We found that similarities between above ground vegetation and the seed bank were the strongest in the earliest successional stages, when annual grasses dominate. Surprisingly, this relationship was driven by the presence of a relatively new introduced annual grass, Ventenata dubia. Finally, the seed bank within cultivated sites had significantly (p < 0.05) more introduced species than noncultivated reference sites, especially seeds of introduced annual grasses. Overall, our results suggest that these sites are native seed limited and could potentially shift to invasive species dominance with further disturbance, especially on historically cultivated areas. These results have important implications for management given the conservation concern for these remaining intact grasslands. In addition, they add to the growing literature regarding the Pacific Northwest Bunchgrass Prairie and seed banks within the grassland biome.