Sounds like a great project! If I were starting out on a project like this, I would start by looking through an edited book of Jung's writings, called "The Earth Has a Soul: C.G. Jung on Nature, Technology & Modern Life", edited by Meredith Sabini. This is a great resource for Carl Jung's own words relating to this topic. I would also look closely at the work of Thomas Berry. Books like "The Dream of the Earth", "The Sacred Earth", and "Evening Thoughts: Reflecting on Earth as Sacred Community" would all be good starting places, as well. I don't think any of these books dwells specifically on your thesis of the relationship between nature and the feminine, but mythology is filled with such references. Good starting places for the relationship between the feminine and nature might be M. Esther Harding's classic work "Women's Mysteries: Ancient & Modern", and Erich Neumann's book "The Great Mother."
I think the first batch I've mentioned should be helpful in making case for "healing and wholeness through the human-nature connection." The connection between and the feminine, or the feminine as a symbol of nature can be made in many ways, I think the books I've listed above on that topic may be a good place to start.
I hope these suggestions are helpful. Best of luck to you on your project!
All the best,
I'll keep looking, Jesse, and let you know if I find anything.
All the best,