Elephant & Piggie: I will Surprise My Friend! by Mo Williams, the famed author of the Pigeon books.
There are 25 Elephant and Piggie books. This one is one of my favorites because the emotion is very genuine. The two friends decide they will jump out and surprise each other. When they lose track of each other, Gerald the Elephant lets his worries about his friend run away with him. Piggie wonders if Gerald left to get lunch.
Elephant and Piggie caters to beginning readers, and frequently employs a repeating sentence structure. Williams also reinforces the ideas with thought bubbles, and lots of expressions on his characters' faces. Most of the pages show the two friends (and occasionally, other animals) on a simple background. It creates a clean and uncluttered look, with a character-driven story.