Here's an unusual wide brimmed, asymmetrical hat. Usually if something has a brim, and is asymmetrical, it has a base closer to the head for a better foundation. This is the case with this 1950s hat, and the brown 1930s hat below. With this hat I placed a hatpin on the side, under the brim and on the base. On the other side, just for good measure and because the area is hidden, I slipped a bobby pin.
This is also an asymmetrical brimmed hat with a base, but I placed a pin at the side, base of the crown.
On 1940s tilt hats, there's usually a band, or base at the back for support. These are perfect for slipping hidden bobby pins, and often don't need a hatpin.