Toadstools are the fruiting bodies of a class of fungi known as Basidio-mycetes. The vegetative part lives underground, feeding on dead plant material and speeding the process of its decay. When the ideal environmental conditions occur, the fungus reproduces via spores produced in the toadstools. These being above ground are dispersed by the wind.
When the supply of nutrients is used up the fungus dies out and no more toadstools are produced. They do not normally occur during the second or third uear after the turf has been laid. The fungus is not a disease, unlike those which cause "fairy rings" in the turf, in fact breaking down dead material is beneficial to the turf. The small brown toadstools that occur most frequently in new turf are not poisonous. However, their consumption is not recommended.
A traditional remend for controlling toadstools is to apply a solutions of 2ounces or Epsom sales (magnesium Sulphate) dissolved in a gallon of water per sq. yard of affected area. As toadstools are mainly composed of water they soon dry up and blow away or can be swept with a besom broom. THey can also be removed with the lawn clippings.