This delightful and delicate little fungus, is a decomposer. That is, it breaks down dead organic material and recycles the nutrients from this material back into the soil. These nutrients then help other plants to grow. The black you can see under the cap marking the edge of the gills are the mature spores. These fungi often don't last very long, they appear out of the mulch or sometimes dung early in the morning and may disappear as the day warms up and dries them out.