To Hear the Angels Sing – Dorothy MacLean – Kindisfarne Press 1990 (A sheer delight)
The Real World of Fairies – Dora van Gelda – Quest 1977 (Another sheer delight)
Nature Spirits & Elemental Beings – Marko Pogačnik – Findhorn Press 1995 (A very good read)
The Kingdom of the Gods – Geoffrey Hodson – The Theosophical Publishing House, Adyar 1952 (A wider ranging classic, readable work)
Nature Spirits (Selected Lectures) – Rudolf Steiner – Rudolf Steiner Press 2007
Meeting Fairies – R. Ogilvie Crombie – Allen & Unwin 2009 (Another sheer delight -Crombie was associated with the Findhorn Community.)
The Magic of Findhorn – Paul Hawkin – Fontana/Collins 1976 – (An account of how the Findhorn Community (Scotland) came about and achieved spectacular success in its vegetable gardens.)
Check out the publications by the Findhorn Community, Scotland.
The Secret Life of Plants – Peter Tompkins and Christopher Bird – Penguin 1974 (All science but a worthwhile easy read.)
Journey into Nature – Michael J. Roads – HJ Kramer Inc 1990 (Australian. Also wrote Talking with Nature.)
Fragrant and Radiant Healing Symphony – Roland Hunt – 1949 – HG White (An oldie but very interesting, only available second hand)
Perelandra Garden Workbook: A Complete Guide to Gardening with Nature Intelligences – Machaelle Small Wright (A popular and longstanding guide)
The Hidden Life of Trees – What they feel, How they communicate by Peter Wohlleben. Recently published in English by Black Inc. (2016) A wonderful new addition to our understanding of trees and forests by a German Forester.
In addition to the above, just do a search using these sorts of phrases:
‘Communicating with trees’, ‘Talking with trees and plants’. You may be surprised how much is out there!
Here’s an interesting article: http://modernfarmer.com/2013/05/inside-secret-world-of-plant-communication/
If you have your own favourites, let me know.