J.R.R. Tolkien, The Silmarillion: At the beginning of the world there were two trees, one silver and one gold, brought forth by the song of Yavanna, Valar of Earth, and the tears of Nienna, Valar of Mercy.

C.S. Lewis, The Magician's Nephew: At the beginning of the world there were two trees, one silver and one gold, because some coins fell out of a guy's pocket lol

It is shocking how much stuff about Narnia and Middle Earth is explained by the fact that Lewis and Tolkien had this mad frenemies thing going on.