The Little Button Elves by Enid Blyton.
 
The five elves were so similar that they were named after the number of buttons on their tunics.
One day, the elves set off for Bumblebee Common for a picnic. They packed a kettle, bread, butter, cakes, apples, and crockery. However, as they crossed a bridge, Three-Button tripped and dropped the cakes into the stream. This was a disaster for a picnic! Bread and butter was fine, but cakes were the best part. Three-Button was very sorry, and since he was the one who dropped the cakes, he was asked to fetch water for the kettle............
 
Illustrated by Rene Cloke.