"In reverence Yavanna is next to Varda among the Queens of the Valar. In the form of a woman she is tall, and robed in green; but at times she takes other shapes. Some there are who have seen her standing like a tree under heaven, crowned with the Sun; and from all its branches there spilled a golden dew upon the barren earth. [...] Kementįri, Queen of the Earth, she is surnamed in the Eldarin tongue."
(from the Valaquenta, in The Silmarillion)
"Then Yavanna arose and stood upon Ezellohar, the Green Mound, but it was bare now and black; and she laid her hands upon the Trees, but they were dead and dark, and each branch that she touched broke and fell lifeless at her feet."
(from "Of the Flight of the Noldor," Ch. 9 of The Silmarillion)
(The phrase "Eä! Let these things be!" is what is spoken by Eru in the Ainulindalė, just before the visible world is created.)
(Thanks to Nath for the quick, thorough, and gentle beta - *sends hugs*)