What you have are some great photos of Macrolepiota dolichaula in fabulous condition. By the time I found ours at home they were all ratty - sigh! The Amanita you have mentioned has a more buff/salmon (pale orange) colour whereas you specimen is white. You tend to find the Macrolepiota dolichaula in pastures or grassy areas. Lovely find.
Thank you very much for the identification. Sorry about all the bad guesses around Amanita! These specimens are/were all very fresh looking, occurring in grass in two patches that can be seen a long way off. I haven't walked over to photograph the second group yet.
You never need to apologise for 'bad guesses' because it's always great to see someone have a go. Let's face it we all do this and I find I always learn more by at least trying. This particular species is often thought by many to be an Amanita and some Amanitas have a very similar look. Amanitas tend to be more robust, not as elegant or as large and associated with trees as they are mycorrhizal. Whereas this particular Macrolepiota is a saprotrophic fungus and found in grassy areas.
Sorry I don't talk about edibility. There's always the chance I could say something is edible and someone could see a fungus that looks like the one I mentioned but in actual fact is something else. My only comment is there is a good range in a number of the supermarkets. Otherwise you have to collect with someone who knows absolutely what they are looking at. Sorry.