by Edith Nesbit
This book is an entrancing combination of magic with the everyday trials of childhood. 'It' is a Psammead, an ancient, ugly and irritable sand-fairy the children find one day in a gravel pit. It grants them one wish a day, lasting until sunset. But they soon learn it is very hard to think of really sensible wishes, and each one gets them into unexpected difficulties. Magic, the children find, can be as awkward as it is enticing.