It ought to have been obvious, from your photos, that there are actually several different fungi in your photos.
There are many flat white fungi, many known as Clitocybe. The various species of Clitocybe vary from edible to lethally toxic. There is also another group of flat white fungi, known as Lactarius, some of which are associated with birch trees. It could be one of them. They also range from edible to poisonous.
The photo of one with a brown cap and white patches is definitely different to the other two. It's not easy to see whether the white patches are simply damage, or part of the fungus. One known as Amanita excelsa is brown with white patches. Said to have an 'unpleasant odour'. There is a chemical test for that one. If the flesh is mixed with sulphuric acid, it turns purple. That's a relative of the famous Amanita muscaria, red with white patches, which is dangerously poisonous.
If you've found at least two, then there may be many more, around that part of your garden, and also even in grass. It just takes a bit of careful observation to see them. More may appear as we get into November. The ones you have are all beneficial to the trees and shrubs in the vicinity.
