An abandoned football?

When I found one of these in the grass near the entrance to Filnore Woods, I thought someone had dumped an old sorbo-rubber football.  Inside it was just like foam rubber. 

But when I found another and then another I realised that these were last year's Giant Puffballs.  Snow-white when they first begin to grow, they get bigger and bigger and then break away from their umbilical cords, which anchor them to the earth, so that they can puff their spores around the place as they roll. Millions of spores are produced, as with all fungi, but only a few will grow to be giant puffballs them selves.