The Mirror of Erised was introduced in Harry Potter and the Sorcerer’s Stone. The mirror caught Harry’s attention because it showed him his deceased parents, which was the greatest desire of his heart. It was also used later to thwart Professor Quirrell.
I purchased this from a wonderful seller on Etsy: Magicbimbo. She has many great Harry Potter ornaments she makes and sells!
I’ve also purchased the Three Brothers ornament, the Azkaban Prisoner Plaque, the Fat Lady Portrait, the Mermaid Window, and the Educational Decrees from her.