The phrase 花笠 literally means "flower hat" and usually associated with two distinct headgears:
Kasa hats decorated with flowers, used for various traditional dance festivals across Japan. -> [photo]
Flower motif hats worn with ryuusou for Ryūkyū(Ryuukyuu) Dance. Sometimes called "Ryūkyū hanagasa" by souvenir shops for the sake of convenience. -> [photo]
This tag is currently used for the latter meaning. For the former, try using ajirogasa and hat flower.