Princes William and Harry (right) paid a quiet tribute to their mother, Princess Diana, on Wednesday, a day before the 20th anniversary of her death. Along with Prince William's wife, Kate, they toured a memorial garden at Princess Diana's former residence, Kensington Palace in London. They also inspected the dozens of bouquets left in front of the palace before Prince Harry laid his own floral tribute, given to him by a member of the public.