Dan Mathews, right, and his mom, Perry Lawrence, are picture perfect in this 2010 photo. Photo: Dan Mathews. A short time after his mother died, Dan Mathews had her ashes scattered in an unorthodox memorial that she would have adored — A small amount of her powdery remains were sprinkled among the artificial snowflakes dropped during “Waltz of the Snowflakes” in a theatrical production of “The Nutcracker.” Mathews, PETA’s senior vice president, includes the story in his new memoir, “Like Crazy: Life with My Mother and Her Invisible Friends.” In the book, Mathews explains how he goes from being a globe-trotting animal rights activist to caring for his 79-year-old mother, who is schizophrenic. ‘The Nutcracker’ Mathews’ mother, Perry Lawrence,