by Nigel Pennick
Nigel Pennick is well known and respected for his books on magic and folklore. This is a good book on Earth-based spirituality. It is not, as the title might suggest, about Elemental Spirits.
The book is about natural magic, in his own words, "It is the power of everyday objects and human actions." I think it's a good starting place for someone interested in nature magic, but not drawn to a specific path or the Pagan religions like Wicca.
Some of the correspondences were different than I've read elsewhere in older sources, like Friday has always been green but Pennick assigns in blue and the purposes of Opal really threw me, but most of them are familiar with just the occasional anomaly.
Pennick gives us an over view of working with minerals and stones, animals and birds, and of connecting to the magic of the Earth in general. It isn't in depth information, but a decent starting point. He covers making magical tools and offers some food and drink suggestions as well as simple rituals throughout.
The one thing I would caution someone new to the subject is that some of the 'rules' like making your own magical knife are not hard and fast. I would look at the information as folkloric and likely to be a little different than another person's path might take them.