Investors looking for staying power in the crowded restaurant sector are turning their attention to Mellow Mushroom, a brand that has quietly built a cult following while delivering strong financial performance. Founded in 1974, the Atlanta-based pizza chain now operates in 15 states with more than 160 locations. Its top quartile averages $3.8 million in annual sales, while systemwide averages sit at nearly $2.7 million, placing Mellow Mushroom among the top-performing franchises in its category.