These data were collected as part of a larger research project, called Grazing Management for Drought Resilience (GMDR), which aims to understand how management strategies impact rangeland ecosystem health across varying drought magnitudes. Growing season droughts have major impacts on grassland vegetation and are predicted to become increasingly frequent in semi-arid prairies of North America, but little is known about how droughts and post-drought legacies interact with grazing management to affect forage quality and quantity. The study was conducted in eastern Montana at the Fort Keogh Livestock and Range Research Laboratory and a private cattle ranch in the Thunder Basin region of northeastern Wyoming. We experimentally manipulated grazing and rainfall reduction in a full factorial design (3 grazing × 5 precipitation levels). Experimental treatments were used to assess both short and long-term changes in forage quantity and quality. Grazing treatments were implemented in early July in Wyoming and early August in Montana. Forage, consisting of living and dead herbaceous material (e.g. grass, forb) was sampled in May, June, and July for 5 years (2019-2023). Samples were dried and weighed to obtain biomass measurements and subsequently ground for analysis of quality including digestible organic matter and percent fiber. In addition, these data include two composite indices of digestibility: relative feed value (unitless index based on digestibility and fiber content) and digestible forage biomass (g × m-2).