cloche hat

The cloche hat is a fitted, bell-shaped hat that was popular during the 1920s.^[1] (Cloche is the French word for bell.) Caroline Reboux is the creator of the cloche hat.
Cloche hats were usually made of felt so that they conformed to the head.^[1] The hat was typically designed to be worn low on the forehead, with the wearer's eyes only slightly below the brim.^[1] By 1928-1929, it became fashionable to turn the brims on cloche hats upwards. This style remained prevalent throughout the early 1930s until the cloche hat became obsolete around 1933-1934.

Often, different styles of ribbons affixed to the hats indicated different messages about the wearer. Several popular messages included: An arrow-like ribbon which indicated a girl was single but had already given her heart to someone, a firm knot which signaled marriage or a flamboyant bow which indicated the wearer was single and interested in mingling.^[2]
Cloche hats' popularity and influence were overwhelming. Couture houses like Lanvin and Molyneux opened ateliers to join milliners in manufacturing the hats.^[1] The hats even shaped hairstyles: the Eton crop (the short, slicked-down cut worn by Josephine Baker) became popular because it was ideal to showcase the hats' shape.^[1]
http://en.wikipedia.org/wiki/Cloche_hatA straw cloche 1920 http://www.1860-1960.com/

A velvet cloche 1920
A cloche from 1920 , straw with embroiderie