Wild Lentinula edodes (shiitake) strains are an important breeding material for developing new varieties suitable for various consumer preferences and environmental conditions. The morphological characteristics of 100 wild shiitake strains collected from 14 regions were investigated in a sawdust block cultivation. The characteristics of their fruiting bodies were diverse. Among them, 38% of the caps was convex, 33% was broadly umbonate, 27% was applanate, and 2% was shallowly depressed. In terms of their stipes, 55, 23, and 22% were the column, clavate, and funnel type, respectively. The shape of the cap was the most diverse on Mt. Hwaak, whereas the shape of the stipe showed various phenotypes from various regions. Even among strains collected from the same forest, different types of mushrooms were observed. In conclusion, wild shiitake strains that have adapted to various environmental stress can be used to develop new varieties. Thus, securing various genetic resources and studying their traits are important for researching breeding technology.