These fungi are often oddly shaped as this one here is. They are often known as the pigskin poison puffball, and they are indeed poisonous. They are called both puffball and earthball, but they are not really puffballs. When cut open they are a lovely violet colour when young, and a deep blackish-purple when mature. You can, if you look closely just about discern the purple colouration where the fungus has broken open.