You may find from time to time that toadstools appear on your lawn.
They are not harmful and may be brushed off. Toadstools indicate increased biological activity and are more common in well fed lawns. They are also more prevalent in humid conditions. If the toadstools grow in a ring this indicates that you have fairy rings. – See more at: http://www.supagrass.co.uk/toadstools#sthash.v9ae7s1U.dpuf