Apparently, the two enjoy mushroom foraging and are "deeply competitive about their hauls," the food writer writes. In the book, as reported by the Daily Mail, Barker Bowles says mushrooms are "somewhat of an obsession" for King Charles and Queen Camilla — the pair even try to out-forage each other.

King Charles and Queen Camilla have an unusual hobby in common that they are said to become "competitive" over.

Queen Camilla's son Tom Parker Bowles spoke about King Charles' health amid his cancer treatment in a new interview with British Vogue.

Queen Camilla is "deeply competitive" with King Charles, according to her son Tom Parker Bowles, amid the couple's constant battle. King Charles is a keen champion of the environment, wildlife and the outdoors.

Queen Camilla "put her foot down" about sick King Charles III not meeting with Prince Harry during the rebel Duke's trip to London in late September. Her Majesty was reported to have been concerned about the monarch's condition due to His Majesty's receiving cancer treatments for over six months after his diagnosis.

King Charles and Queen Camilla are remembering Dame Maggie Smith . On Sept. 27, the King released a statement following the distinguished British actress' death at age 89.

The little-known fact was revealed by Camilla's son, Tom Parker Bowles, who said King Charles and his mother were 'deeply competitive' about one unexpected hobby