In a note that was tucked into a wreath of flowers and foliage chosen by Charles, the new king wrote, "In loving and devoted memory."
Charles signed the note with his first name, Charles, followed by the letter R, which stands for Rex, the Latin word for king.
The king, the eldest of the queen's four children, has led members of the royal family and the public through more than one week of mourning for the queen, who died on Sept. 8 at age 96 while at Balmoral Castle in Scotland.
Charles was by his mother's side when she died and walked directly behind the queen's coffin as it was escorted into Westminster Abbey Monday for her funeral.
The floral wreath that held the note written by Charles was full of bright flowers cut from the gardens of the royal family's residences, as well as foliage of rosemary and English oak.
In a sentimental touch that came at the request of Charles, as did all the flowers chosen, the foliage in the wreath also included myrtle that was cut from a plant grown from myrtle that used in the queen’s wedding bouquet when she wed her beloved husband Prince Philip in 1947.
The queen will be buried next to Philip at the King George VI Memorial Chapel at St. George's Chapel on the grounds of Windsor Castle.
The burial service will be private, attended only by members of the royal family.
Before the queen is buried, items on her coffin will be removed.
In addition to the wreath, the coffin is adorned with the Imperial State Crown, the crown that monarchs wear as they leave Westminster Abbey after the coronation.
The crown -- which contains 2,868 diamonds, 17 sapphires, 11 emeralds, 269 pearls, and four rubies -- was made in 1937 for the coronation of the queen's father, King George VI, according to Historic Royal Palaces, the organization that oversees the Tower of London, where the crown jewels are held.
The queen's coffin is also adorned with the Sovereign's Sceptre with Cross and the Sovereign's Orb, both part of the coronation regalia.
The queen's coffin is draped with the Royal Standard, the flag representing the sovereign and the U.K. During her reign, the Royal Standard was flown on her car and aircraft on official journeys and at royal palaces when the queen was in residence.