GIANT PUFFBALLS--Moonrocks? No. Pumpkins? No. They didn't make the Guinness Book of World Records, but the giant puffball mushrooms two sisters found along Huron Parkway did make a good dinner for a family of seven. Michelle Horn, 13, and her sister Donna, 14, of Chelsea, found the overgrown fungi while walking from their school near Veteran's Hospital, where their father works. They planned to feast on one of the mushrooms and freeze the rest for later. Michelle's, on the left, weighed in at 6 pounds, 28 oz.; the one in the middle, held by their father, Don, is a normal sized puffball; and the one on the right, held by Donna, weighed 9 lbs., 11 oz. The world's largest recorded puffball weighed 18 pounds, 10 oz., according to the 1982 Guinness book.