Oyster mushroom (Pleurotus ostreatus) mycelia made 52 aroma compounds when grown on amaranth seed and Bambara groundnut media. Amaranth brought out stronger mushroom, green, and fatty flavors, while Bambara pushed the flavor toward malty, nutty, fermented, and lightly floral notes. Both mycelia were high in protein, reaching 35.8%–38.2%, with glutamic and aspartic acids adding natural umami potential for future plant-based foods.