References
This is by no means the complete set of references that I’ve used while studying reiki, but this is the list of, “If you were to only read one book, this is the one I would recommend to you.”
Magick of Reiki: Focused Energy for Healing, Ritual, & Spiritual Development by Christopher Penczak.
Eastern Body, Western Mind: Psychology and the Chakra System As a Path to the Self by Andorea Judith
Nature-Speak: Signs, Omens and Messages in Nature by Ted Andrews
Taking Up The Runes: A Complete Guide To Using Runes In Spells, Rituals, Divination, And Magic by Diana L Paxton
Ogam: Weaving Word Wisdom by Erynn Rowan Laurie
The Tarot Handbook: practical applications of ancient visual symbols by Angeles Arrien
Love is in the Earth: A Kaleidoscope of Crystals - The Reference Book Describing the Metaphysical Properties of the Mineral Kingdom by Melody (Author) & Julianne Guilbault (Illustrator)
On a side note, I would also recommend getting native plant guides for your region. I personally have enumerate books on tree and wild flower identification as well as Remarkable Plants of Texas, Edible and Useful Plants of Texas and the Southwest, and many books upon medicinal uses of plants. It’s extremely important to work with the native plants of your region as they are readily available, free, and more power than anything you could order and import. Plus, knowing the history of the plant in your region will often open new possibilities or substitutions for European plants.