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.

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

Thanks,

--
Chris