The ghosts of light bulbs.  From Graphs: How to Make and Use Them by Herbert Arkin and Raymond Colton, 1940.

"Ghost party."  From Susquehanna's 1914 yearbook.  See Of Feeding & Caring For Sheet Ghosts.

Memories of college.  From Elon's 1915 yearbook.  See How to Hoodoo Hack a Yearbook.

From Pan's Garden by Algernon Blackwood, 1919.

From There is No Death by Florence Marryat, 1891.

There's always one guy whose eyes wander from the camera, even when all the guys are you.  From Millikin's 1971 yearbook.

The phrases "ironed sheet ghost" and "laundered sheet ghost" are both Googlewhacks, delivering zero results.  But we may have ruined that with this controversial new release: Of Feeding & Caring For Sheet Ghosts..  Some folks are saying that the booklet doesn't actually exist.  We offer proof, but as with seemingly all paranormal issues, not everyone agrees on what constitutes actual evidence.

These ghosts haunt Lehigh's 1974 yearbook.

From Susquehanna's 1907 yearbook.

Here's one way people can become ghosts when a yearbook gets scanned.  To understand this, see The Ghost in the [Scanning] Machine.   See also How to Hoodoo Hack a Yearbook.

From the Michiganensian yearbook, 1911.

From Lustige Blätter, 1918.