Big

This is about 35 or 40cm across. This may be a 'dyads saddle' mushroom and I can certainly see why it might get that name.
It is supposed to be edible, however I shall not be putting it to the test
I've always fancied being able to pick mushrooms but here are thousands of fungi, most just inedible but not harmful, a small selection are edible, a selection poisonous and a few deadly.
I'll stick to Sainsbury's