More mushrooms

Nick has gone mushroom hunting in the grass outside the front of the
house. This is a photo of the bowl he picked:

They are white, yellow markings where damaged or apparently sunburnt.
The gills are pink. They seem to be growing in a big circle, on grass,
with no bits below the soil level

There are also lots of other types, including some huge flat ones with
dark gills, which I thought were mature versions of this one, but they
do appear to be different.

We're /fairly/ sure they're safe, as one of our neighbours eats them!
But mushrooms still scare me when they're not from the supermarket. :-(

Any thoughts?