I'm finding that Clifford the Small Red Puppy books are very repetitive, with Clifford stowing away to end up in an unexpected place, briefly getting lost, and/or causing accidental messes. But Clifford as a puppy is so adorable, I just don't mind that much. Here he ends up lost in a big basket of mail at the post office and the postal workers get waaaaay to excited when he is found again. ( )

Emily Elizabeth and clifford make a valentines day card for her grandmother. they take it to the post office where clifford gets stuck in a box of letters. luckily they find him and they even recieve a letter back.
1 book

Emily Elizabeth tells about Clifford's first Valentine's Day when he was still a tiny puppy. Clifford goes to the post office with Emily Elizabeth to mail valentines and gets lost in the carts full of letters. Paperback copy.