If you're looking for "dabbling in Mandarin" books, you might try Huy Voun Lee's books. (At the Beach, In the Snow, In the Leaves, 1 2 3 Go)

FWIW, DD7 has lived in a bilingual Mandarin / English home her entire life, and her knowledge of spoken Mandarin is limited to good morning / good night / goodbye / love you / thank you. She doesn't read / write at all.