This is a Parasol, Macrolepiota procera.
I’ve seen Parasols before with a clear faerie ring over 60m wide in a high mountain plateau in Italy:
I’ve also found Shaggy Parasols on Dartmoor:
This one is on its own. I can see it from the other end of the field. I know what it is even before I’ve walked over to it.
They’re always a pleasure.