This woven bamboo/straw hat is from the family of oriental rice paddy or coolie hats, although as can be seen its not the typical conical style.
I've so far found it hard to obtain much information on these styles of hats so can't tell you much more, other than it provides good shade and having a chin strap is essential even in a slight breeze.
The is hat gets used by The Incredible Wang, master of Chi and full of wise words, he also makes good noodle soup.
I bought this hat from a Larp fair trader who does not seem to exist any more, at least the website link I have doesn't work and not seen them trading for a few years perhaps re-branded.