Book excerpt: Did you know President John Quincy Adams had a pet alligator? He kept it in a bathtub in the East Room of the White House. But President Adams wasn't the only commander-in-chief with an unusual pet. Along with a menagerie of dogs, cats, horses and birds, presidents and their families also had pet snakes, raccoons, bears, cows, mice, and more. Meet Thomas Jefferson's mockingbird, Dick, who ate from the president's mouth; Warren Harding's dog, Laddie Boy, who was served a birthday cake made of dog biscuits; and Teddy Roosevelt's pony, Algonquin, who rode up the White House elevator.President Adams' Alligator teaches children about the presidency through pets of the presidents, from George Washington to Barack Obama.