horse manure expert needed!!

Now then,we all know what horse dung looks like in the road or on the pavement,don`t we?

However,this stuff has been rotting for a few weeks now ,I am collecting it from the back of the pile at the stables. Some of it has a grey or even white covering to it.
Is it mushrooms that cause this colouring?It seems to happen in the pile in patches,especially where its very dry.There are mushrooms growing in the heap in quite a few places.

Should I carry on putting this part of the pile on my heap or leave it behind and just take the dark coloured dung?

hey willowish,it will be stacked or on the ground for 10-12 months before it`s used,like I did last year,it was the white colouration on the outside I was wondering about,thought it might be the mushroom spawn causing it.I think I ask too many questions 

I had mushrooms splurting out too, so didn't worry Carollan.

Just let the whole lot fester for several months, and then, get going with either the double digging, or the spreading - whichever you choose!

Wait awhile though, because that stuff is potent! At least 6-9 months...