This top-down hat is quick (5 hours or so) and fun, using Kauni yarn triple (Navajo style), which is described in the pattern and in this Youtube video.
There are two warm brim options, plain or with decorative scallop holes. The whole hat may be worked on one long circular needle, on two circulars or on a set of dpns according to your preference.
Pictured in Heavenly Shades of Night with Green Riot for the brim; Sunburst for the brim; Watercolour; Purple Night; Morning Mist with Ocean for the brim; Earth and Sky; Sunburst with Purple Night for the brim
This hat is also available as a kit.