Magic Nuts - Mary Louisa Molesworth

A delightful children’s story about Leonore, a little English girl, taken by her governess to Fraulein Elsa’s home town in an (unnamed) country where she meets Hildegarde, a little girl of her own age, who lives in a castle there. The girls each come into possession of three magic nuts, which open the doors to three enchanted adventures involving gnomes, air-fairies, and mermaids. - Summary by Winnifred Assmann