The Very Lonely Firefly by Eric Carle is the story of a firefly searching for other fireflies. Along the way he finds other lights like a lantern and a candle. Once he finds other fireflies, he's happy to be flashing right along with them.
I've always loved this book. Mine was a gift from a dear friend so it has special meaning.I would recommend finding a copy that has the lights at the end. They make for a special surprise.