2-Azahypoxanthine (AHX, 1) and imidazole-4-carboxamide (ICA, 2) were isolated from a fairy-ring forming fungus Lepista sordida. AHX was converted into a metabolite, 2-aza-8-oxohypoxanthine (AOH, 3), in plants. Afterward, it turned out that these three compounds, fairy chemicals (FCs), endogenously exist in plants and are biosynthesized via a new purine metabolic pathway. FCs gave tolerance to various stresses to plants and regulated growth of all the plants tested. Furthermore, some metabolites of FCs were found. In addition, FCs increased the yields of rice, wheat and other crops in green-house and/or field experiments.