The appearance of toadstools in a garden should not usually be a cause for concern. You should, however, become familiar with the fruiting bodies of the few species such as Armillaria and Marasmius that can cause problems, as well as the symptoms of the respective diseases that they.
While most fungi don't actively harm plants, honey fungus (Armillaria spp.) is an exception. Keep a look out for the toadstools in autumn, and see the profile in our Also see section above.
For much of the year, fairy rings are just seen as a darker ring of grass. However, in autumn, they are often marked by toadstools.