we knew only what we had gleaned from mom 's rare but unsettling bedtime stories about the `` mushroom dwellers of ambergris , '' and a brief description from a book for children that had delighted and unnerved us simultaneously : fifty mushroom dwellers now spilled out from the alcove gateway , macabre in their very peacefulness and the even hum-thrum of their breath : stunted in growth , wrapped in robes the pale gray-green of a frog 's underbelly , their heads hidden by wide-brimmed gray felt hats that , like the hooded tops of their namesakes , covered them to the neck .