Quite often people leave little offerings to the various Gods and Goddeses they put their faith in. This practice is most common among Pagans but is not limited to them only. It is the Pagan equivalent of lighting a votive candle in a Christian Church.
These are usually left attached to a tree at sites of special spiritual interest such as holy wells. Quite often they are just a piece of ribbon tied to a branch, but sometimes people put a lot of effort into creating something special. This one caught my eye when I visited the Holy Well at Menacuddle.