I agree with the genus Amanita though not ochrophylla group sorry! Stem too 'fluffy' and gills would have tones of orange/yellow. You are correct about most Amanitas having white gills though. There are always exceptions that prove the rule. There is one with green gills - Amanita austroviridis! And a delightful one with 'pink' gills Amanita roseolamellata. So if you're lucky enough to come across either of these species you'll be able to identify them now! You've been making a great contribution.