Peoria State Hospital maintains a reputation as a haunted spot. Claims are that the area is still inhabited by the ghosts of many former patients. The idea is probably perpetuated by the fact that there are four on-site cemeteries, because Zeller implemented a system for burying the hospital's unidentified deceased. One specific ghost yarn tells of the spirit of "Old Book," a patient who dug graves at the hospital until his own demise. It is said that upon his death he took over the physical form of a tree on the grounds dubbed the "Graveyard Elm". Locally it is known as the "crying tree." Though several attempts have been made at removing the tree it still stands at the hospital.

In the 1920s, Zeller penned a book titled, The Bereft, drawn from the mysterious experiences he had at the hospital during his two tenures as superintendent, 1902–1913 and 1921–1935. Included, among numerous other eerie stories, were Zeller's own account of Old Book and the Graveyard Elm

Old Book is the name given to a purported ghost or spirit which haunts a cemetery and tree on the grounds of the Peoria State Hospital in Bartonville, Illinois. While rumors of ghosts and ghost stories are highly speculative the Old Book tale has been documented many times. Included among those documenting the tale is the first director of the state insane asylum, George Zeller.

The superstitious tale surrounding Old Book is somewhat unique among ghost stories in that it was reportedly witnessed by hundreds of people. The story goes that when Old Book died his funeral was attended by hundreds of patients and staff members who became witnesses to the ghostly phenomena that was about to transpire. As workers were attempting to lower what should have been a heavy casket they discovered that it, in fact, felt empty. Suddenly a crying sound echoed from the Graveyard Elm and everyone in attendance turned and looked, including Dr. Zeller. They all claimed to have seen Old Book standing by the tree. They so believed it to be true that Zeller had the casket opened to ensure that Old Book still lay inside. As the lid was opened the crying ceased and Old Book's corpse did, in fact, lay inside the coffin. Days passed and the tree began to die. While several crews have tried to remove the Graveyard Elm or the "crying tree," as it is also known, none have been successful citing the weeping emanating from the tree