That's a ghost in the tree, according to our custom Uncanny Detector app.  From the Regis yearbook of 2006.

From North Adams' 1975 yearbook.

From Richmond Technical Institute's 1980 yearbook.

From Tulane's 1980 yearbook.

This photograph may be used to facillitate time travel.  From the Western Ontario yearbook of 1961.

Our custom Uncanny Detector app positively identified the shadowy figure as a ghost.  From Lehigh's 1974 yearbook.

Memories of college.  From Elizabethtown's 1972 yearbook.

"The dark dangerous forest is still there, my friends. Beyond the space of the astronauts and the astronomers, beyond the dark, tangled regions of Freudian and Jungian psychiatry, beyond the dubious psi-realms of Dr. Rhine, beyond the areas policed by the commissars and priests and motivations-research men, far, far beyond the mad, beat, half-hysterical laughter... the utterly unknown still is and the eerie and ghostly lurk, as much wrapped in mystery as ever." —Fritz Leiber (via 1five1two)

More glowing trees, part of the eerie forest that spreads through all vintage yearbooks.  From Berea's 1958 yearbook.

This photograph may be used to facilitate time travel.  From the Wake Forest yearbook of 1968.

From Elmhurst's 1960 yearbook.

Memories of college.  From Memphis State's 1991 yearbook.

This photo may be used to facilitate time travel.  From Wake Forest's 1973 yearbook.

To best see pirate ghosts haunting the seashore, we first go purblind.

From Bookbindings Old and New: Notes of a Book-Lover by Brander Matthews, 1895.

"Fog-bow among the mountains."  From The Dew-Drop and the Mist by Charles Tomlinson, 1847.

INSTRUCTIONS: Add fog (courtesy of the tissue paper scanned by Google Books).
From A Strange Story by the author of My Novel, 1864.

"Do you remember the night you came through the fog?" from Pearson's, 1910.