The grey puffball (Bovista plumbea) always occurs in a 'troop' or cluster. It is widespread and common occurring on grassland and can be found on coastal downland (like these at Durlston), in pasture, even on golf courses, in summer and autumn. The ones in my photograph were taken late in the year and have lost there spores through the hole in to top of the dome. They have also faded in colour too, they can be much whiter when fresh.
Not a fungus for eating unless you like a lot of powder.