In message , Al
writes
I have a couple of "clumps" of toadstools growing on the lawn. The
biggest area of the two is probably 20 or so of the buggers, clumped
into a circle the size of a dinner plate. They're a light brown colour
but don't know what species they are or whether that is relevant.

Probably Fairy Ring Champignon.

What's the best way of removing them and ensuring that they don't
re-occur?

They'll burn themselves out soon enough. We usually get a ring or two in
the Autumn, but they don't last long and don't do any damage.

You could eat them if you want to get rid of them quicker [Disclaimer:
Get a proper ID on them first!]

Al.
If they are fairy rings then what you will have is very green lush grass
around the perimeter and dead grass in the centre.

They are very difficult to get rid of as you will find if you google
them. (Look at RHS site)

The method I have used is to fork the ground around them starting at the
outer edge and working inwards, then soak the ground daily with
detergent and water.

SO far it seems to have worked and the grass is recovering.
--
hugh
It may be more complicated but is it better?