Dogger by Shirley Hughes. When Dave loses his favourite toy, Dogger, he is desolate. But then Dogger turns up at the school summer fair, and everything seems all right - until someone else buys him before Dave can get the money!
The Pout-Pout Fish by Dan Hanna. Whenever I read this for a storytime, kids start giggling as soon as I repeat the refrain of "I'm a pout-pout fish with a pout-pout face. So I spread the dreary-wearies all over the place.
Everyone in her family says Lily is too loud. She is too loud at home - she wakes the baby. She is too loud at school too. But when Miss Loopiola comes to teach drama, Lily Hippo finds she is just loud enough for the school play!