I like the idea and I say put the biome next to a forest at the bottom of a mountain because geographically all the rain is lead to one side of a mountain so if the moisture is all sent down to the very bottom of the mountain more moss and moisture would be present which when surrounded by a large forest is the perfect recipe for, a great big wet fungus mossy biome with large mushrooms and rotten tree matter. so i say put it at the base of a mountain surrounded by trees.