The first I remember seeing these hats was in the mid 60's. Pilots in the 1st Cav. had taken to wearing them.The hats were only part of it, spurs and buck skin jackets also appeared. I even remember sabers being affixed to doors on Hueys. The name John Wayne was sometimes used referring to those who wore this hat.
I also remember the Army having a green large brim hat that folded up on one side. Later on it became part of the WAC uniform. The only name I can remember for these hats I can not put into writing here or use in polite society. :-"