에 든

that someone likes; pleasing to someone

→ 에
phrase Very common #552
that someone likes; pleasing to someone Often appears in 마음에 들다, meaning that something is pleasing to someone or that they like it. 에 든 is the past-tense modifier form used before a noun.
KO: 제가 마음에 든 가방이에요.
EN: It's a bag that I liked.