Gently rinse the dried lily flower buds, wood ear mushrooms, and shiitake mushrooms with tap water and transfer them into three bowls. Add 1/2 cup hot water to each bowl to cover. Let soak until tender throughout, 30 minutes or so. Once done, squeeze out the marinating liquid back into the bowls and gently rinse them with tap water again to remove any dust on the surface. Slice the shitake mushrooms. Cut the lily flowers in half. And chop the wood ear mushrooms into small pieces. Reserve the marinating liquid from the shiitake mushrooms and lily flowers for the gravy.