We have a couple of dozen or so mushrooms growing in our lawn again. This happens every year. I don't know whether they are edible (personally, I don't eat mushrooms). In any case, they are important or the well-being of the trees (they are a catalyst in the storage of nitrogen in the soil).
A made a reference to the "mushroom cycle" in May of last year: http://penmachinedad.blogspot.ca/2013/05/the-fixer.html
I'm always astounded when these mushrooms appear quite suddenly, apparently "out of nowhere".
Nature is amazing.