Passage: Perhaps the most famous and enigmatic skull was allegedly discovered in 1924 by Anna Mitchell-Hedges, adopted daughter of British adventurer and popular author F.A. Mitchell-Hedges.  It is the subject of a video documentary made in 1990, Crystal Skull of Lubaantun. It was examined and described by Smithsonian researchers as "very nearly a replica of the British Museum skull—almost exactly the same shape, but with more detailed modeling of the eyes and the teeth."

Question: When did F.A. Mitchell-Hedge's adopted daughter discover the enigmatic skull?
1924