Idunna or Idun is the beautiful Norse Goddess of youth; Her name, more properly spelled Iðunn, means 'Rejuvenator' or 'Ever Young'. She grows the golden apples that keep the Gods young. Her husband is Bragi, the God of poetry, Who is sometimes then called by the title 'Husband of Iðunn'.
Iðunn was once kidnapped by the giant Thjazi, Who took Her far away to his home; without Her, or Her apples, the Gods soon grew old. It was soon discovered that she'd last been seen with Loki, Who had orchestrated the whole abduction, and He was threatened until He brought Her home. Borrowing Freyja's falcon cloak, Loki flew to Thjazi's home and transformed Iðunn into a nut, which He brought back to Asgard, the home of the Gods.
Her association with both apples and nuts links Her to fertility, naturally enough; there are also hints that She has an Otherworld nature. Apples and nuts are both associated with the Otherworld, and have been found in Germanic graves; and Iðunn Herself is said in the poem Hrafnagaldr Óðins to be 'of alfen [elven] race'.
I've also done other art of Idun, as part of the World Goddess Oracle.