We review edible mushrooms in South Korea, primarily focused on oyster mushroom (OM) (Pleurotus ostreatus), which shows the highest production among the mushrooms grown for industrial purposes, and it takes up almost 32% of the total production. We aimed to describe their historical uses, common cultivars, and specific characteristics that make them one of the most viable food sources or functional materials. About 15,000 mushroom varieties are known, and 2,000 varieties are possible as human food. Generally, OM has long been studied the most widely as an edible mushroom compared to the other mushrooms in South Korea. Recently, there has been a growing interest in food mushrooms as the production of O.M. is characterized by low greenhouse gas emissions compared to animal breeding in South Korea. Also, OM is often highlighted as nutritious side dishes to serve with rice. Thus, facilitating O.M. production and consumption could contribute to human health and environmental conservation in the near future. Over the years 2015–2020, Pleurotus sajor (PS) export increased by 189.9% (US$ 130,000) compared to 2010-2015. The O.M. cultivation tends to increase rapidly in developing countries for human food and compost or insect foods after cultivation, for example, internal use of culture media or sawdust dump of willow growing environmental conditions. In South Korea, mushroom research has started in the 1960s by the horticultural research center of Rural Development of Administration. In the early 1970s, OM cultivation methods using paddy straw were first developed globally. In 1974, NONGGI-2-1-ho cultivar was developed. In 1976, various practices for water management, disinfection, and fermentation were developed, resulting in substantial yield increases. From 1986, labor-saving paddy straw binders, cutting machines, disinfection boilers, wager suppliers were produced and started being supplied to the farmers. In the 1980s, cotton waste was used as a substrate for cultivation of OM, where water content was identified as the dominant controlling factor for yields. Cotton waste is the best substrate material for summer OM. After using cotton waste, it is commonly replaced with paddy straw. Recently, growers use poplar sawdust, oak sawdust, and rice bran mixed at a ratio of 40:40:20 (v/v/v) instead of cotton waste. When adjusting the nutrients of a medium, the nitrogen content is the crucial factor in determining the yield of OM. There is an additional attempt to add functionality by using alternative plant materials, such as Hovenia dulcis known for liver protection and anti-cancer effects, as well as Acer tegmeutosum and Rhus verniciflura. Further research is in progress to search for and new medium materials effective for OM cultivation.