While I was strimming back some nettles in the "welcome area" just inside the main entrance to Filnore Woods, I noticed a round, white boulder lying in the grass.

Closer examination revealed a giant puffball.  This is the fruiting body of a fungus which spreads its mass of white threads under the soil.  When it is full grown and mature, the puffball breaks free of its stem and rolls around, puffing spores (like tiny seeds) out over a wide area.   

Compare the picture below with the photo I posted in February entitled "an abandoned football?".