They wear a velvet mortarboard, similarly trimmed with gold braid and tassel.
From the en.wikipedia.org
Like the tassel on a mortarboard, Grad Night punctuates the season.
From the ocregister.com
For her graduation in 1946, she wore white earrings to match the white gown and mortarboard.
From the nytimes.com
There is a version of the mortarboard that is worn during mourning.
From the en.wikipedia.org
Early students wore a mortarboard or trencher, although this had been discontinued by 1871.
From the en.wikipedia.org
Multimillionaire Schwarzenegger couldn't make the ceremony but tipped his mortarboard in thanks.
From the upi.com
Epstein tips his mortarboard to these classic American gogetters.
From the time.com
For caps, the mortarboard is recommended in the Code, and the material required to match the gown.
From the en.wikipedia.org
Holly, in black robe with a red tassel on her mortarboard was out there, seated, after marching in.
From the post-gazette.com
More examples
A square board with a handle underneath; used by masons to hold or carry mortar
An academic cap with a flat square with a tassel on top
The square academic cap, often called a mortarboard (because of its similarity in appearance to the hawk used by bricklayers to hold mortar) or Oxford cap, is an item of academic head dress consisting of a horizontal square board fixed upon a skull-cap, with a tassel attached to the center. ...
A board about 3 feet square on which mortar is placed for use by a mason on a scaffold.
Academic cap with square flat top attached to round cap, adorned with projecting long silk tassel. Still worn at educational functions (5)