I sort of recall a knit cap??
Ah, the youth of today...
Jughead in Archie comix wears a beanie, as do stereotypes of nerds in some advertisements, especially beanies with propellers. Beanies are actually felt caps that are just rounded to fit the dome of the head, often but not always with a turned up brim, sometimes crenellated or chevroned.
But for some reason for about the past 15+ years, people have been calling knit watch caps and other knit caps "beanies".
Here are some classic beanies, as opposed to knit caps:
a REAL beanie from the 1950s
an Archie comix fan-boy beanie from a couple score years ago.
A modern-day joke geek beanie with a propeller
Engineers were sometimes called "propeller heads" long ago, and the name was passed along to computer geeks in the 80s.
This is no doubt TMI, but at least it's safe TMI