My 4 year old loves books by Arnold Lobel, Janell Cannon, Mem Fox, Cynthia Rylant (Henry and Mudge and Annie and Snowball books are fantastic), Kevin Henkes, Clifford books, we like Anansi and the Moss-covered rock. Some of our other favorites are: Where the WIld Things Are, Kitten's First Full Moon, the classics, Corduroy, Blueberries for Sal, Make Way for Ducklings, Chicka-Chicka-Boom-Boom, Birthday Monsters (Sandra Boynton), Brown Bear Brown Bear, Over in the Meadow, All the Places to Love, Gussie and Gertie... so many more.
Don't get rid of the books shes "outgrown!" These books are perfect for her to read to you. She will learn sight words and concepts about print from reading and rereading familiar stories. Sandra Boynton's books and Bill Martin Jr.'s books are perfect for this.