Māhū

Māhū is a traditional third gender from Native Hawaiian culture. In pre-contact Hawai'i, māhū were notable priests, healers, and teachers, usually of hula dance and chant. Māhū often performed the roles of goddesses in hula dances that took place in temples which were off-limits to women. Māhū were also valued as the keepers of cultural traditions, such as the passing down of genealogies.

Māhū translates to "in the middle". A similar term is mahuwahine which as coined by Hawaii's queer community in 2003, coming from māhū (in the middle) + wahine (woman). The term mahuwahine resembles a transgender identity that coincide with Hawaiian cultural renaissance. Māhū and mahuwahine can be thought of as umbrella terms that include all trans and non-binary identities.

Flag
The māhū flag was designed by an anonymous submitter to the Tumblr blog ask-pride-color-schemes on January 20, 2016. The colors come from the Kanaka Maoli, which is a flag made to represent Native Hawaiians. The plant is known in Hawaiian as pamakani mahu.

Resources
https://www.deviantart.com/pride-flags/art/Mahu-2-871972206