Mysterious plant at Campobello. Can you identify it?

I follow your blog with great interest. Recently our horse chestnet tree sprouted these weird looking balls. I thought at first that they might be some kind of fungus. They started off white , then turned Gray. I am enclosing the photos as I sent them to Harold Bailey at the Roosevelt Campobello International Park and he suggested I ask you.

Thanks in advance for your help,

Sincerely

Victoria Cunningham

President, Campobello Tourism Association

Campobello Island, NB
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Editors Note: Looks like a puffball perhaps. I did a search, but had no luck. Does anyone recognize this beautiful, strange growth.