Mushrooms have been an integral part of ancient food consumed by man as mentioned in Vedas. Like other vegetables, the mushrooms contain about 90% moisture and are basically included among low calorie food. Mushrooms are rich in fiber, quality protein containing lysine and tryptophan and rich in lenolic acid. Cholesterol is absent and in its place ergosterol is present which can be converted into vitamin D by the human body. These are good source of vitamin B complex especially rich in thiamine, riboflavin and niacin, folic acid and vitamin B12 which are absent in most of the vegetables. Most of the compounds present in mushrooms are classified as host defensive potentiators (HDP); these compounds include poly-saccharides, peptides, nucleosides, triterpenoids, alkaloids, complex structures, and other metabolites produced by mushrooms. It is suggested that regular consumption of different varieties of mushrooms not only protects human beings from heart trouble but also had medicinal potential for certain ailments. Different agro-wastes like paddy straw, wheat straw, sugarcane bagasse, cassava bagasse, coffee waste, leaf litter of forest trees have been used to produce a variety of Pleurotus spp. Various supplements like gram flour, maize meal, and soybean powder are used to enhance the biological efficiency. An experiment was conducted to find out best possible use of organic office waste. A large amount of paper, threads, jute string, card board, etc. are commonly presented as office waste. Of these paper and cotton (cellulose) was used in combination with paddy straw. The results are indicative of better biological efficiency (B.E.) at 50% proportions of cotton and paddy. However, the B.E. was more than 90% in paddy straw mixed with 25% of the waste paper substrate. A large number of smaller basidiocarps were produced in the repeated trials. This chapter describes role of enzymes in substrate utilization. The technology can be effectively used to manage the huge agro as well as biodegradable municipal solid waste. The mushroom cultivation is an important component of circular economy as after cultivation the spent mass can be used in a variety of ways. It can serve as an effective tool to reduce the air pollution caused by stubble burning and deter climate change. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022.