How to identify a puffball mushroom? Or a football?

A puffball mushroom - not a white football but looks similar

A lovely gentleman just came to my door asking permission to go into the field next to us as he thought he'd seen a puffball mushroom growing in there.  This was too good an opportunity to miss so i went with him armed with video camera for what i thought would be a great opportunity to film a foraging piece about mushrooms, how to identify which are safe to eat, where they grow, etc.

I called, Matt, the farmer, to get his permission, as it's his field and you can't just go walking across field without permission.  He was little taken aback and checked which field I meant only to respond "are you sure it's a puffball mushroom, there's been a football in that field for months!"

OK so now into the territory of how to identify mushrooms from footballs.  The lovely chap was very embarrassed when I repeated the conversation but we went anyway, climbing over gates, talking nicely to the horses, avoiding horse poo to gaze lovingly onto the most wonderful........large white football.  Disappointing but he had a sense of humour and has promised that he'll keep looking and if he finds one he'll pop round with it, a puffball mushroom that is, not a football, we have one of those in the field next to us.

They do look similar though don't they, don't think they'd taste similar though.