冠 is one of the most commonly used Japanese kanji, and it also has a lot of special readings in addition to the standard onyomi and kunyomi readings.
ONYOMI 音読み
かんむり kanmuri
KUNYOMI 訓読み
カン kan
Examples
絵の中の少女は黄金ではなくて花のかんむりをかぶっています。The girl in the picture is wearing a crown not of gold but of flowers.マユコは花の冠をつけていた。Mayuko wore a flower crown.先生は生徒の作った花の冠をかぶった。The teacher put on a crown of flowers made by her pupils.