After I put my last post up, I had a look on the internet to see if there was anything about coins being hammered into trees, and to my astonishment there were several quite detailed articles about it.
Apparently there is a growing revival of this tradition of making a wish and forcing a coin into the bark of a (usually) felled tree, or a tree stump. I found articles about it from Wales, Scotland and England, so it is a much wider known folk spell than I had realised.
Up to now, I had only come across the traditions of hammering nails into trees, or tieing bits of cloth or ribbons to them. But in both those cases the trees would be living. Traditional Wishing trees are usually living hawthorn trees and usually overlook a natural spring. You make a wish then tie a piece of your own clothing, or a ribbon to the tree, as an offering. This relatively new phenomena of using coins utilises dead or felled trees, either the trunks of the trees, or sometimes just the remaining stumps.
I haven't yet found out what makes a particular tree a candidate for becoming a Wishing Tree in this way, or whether any felled tree or tree stump can be used in the same way - I get the feeling that this might be the case.
Having read some of the articles, it seems that this may be something that many people are doing just because they see that other people already have done it. In other words they are simply copying the behaviour. Sometimes this happens to trees on private land, or that owned by the National Trust, and one confused National Trust person was quoted as saying 'Why are people wasting their money like this, they could give the coins to the National Trust and we could do something with it!'
The leaving of a votive offering in return for a wish is a very ancient behaviour, it goes way, way back into the mists of time, and seems to be something humans just can't help doing.
In Hull, one of the shopping centres has an indoor pool with a fountain in it. If you look in the pool you will see that the floor of the pool is full of coins of all different denominations. This pool in a modern shopping centre has become a 'Wishing Well'. There are no signs up telling people to make a wish and throw a coin in (in fact sometimes signs are put us asking people to refrain from throwing coins into the fountain), and periodically the management order a clean up and the coins are removed and given to charity. But it is not long before coins are once more being thrown into this pool.
People need magic in their lives.
They need to be able to ask for help from some supernatural power.
I find it very interesting and encouraging to note that even in these modern days of computers, when people seem to be getting further and further away from nature, new magics are still finding their way into the world.