Parasoll Mushroom (Macrolepiota procera)
It is quite common and can be found almost anywhere in meadows, grassy glades and along hedgerows and roadsides. Here in Purbeck it can be found on grazed grassy areas amongst the heath.
The cap of this fungi can grow to be as much as 10" across and, as a result, is quite easy to identify especially with its crusty brown top. The book says it is excellent eating but I am not sure I am going to try it!