Hawthorn berries are very popular among professional and amateur herbalists. They are high in vitamin C and have also been used for a range of heart conditions for over 2000 years. There is scientific research to show the positive effects of these berries in dilating coronary arteries and improving oxygenation of the blood. Apparently they also normalise blood pressure. Hawthorn berries are used for insomnia, to help digestion and for coughs and colds. They are also considered to be a symbol of fertility.
Locally, in Powys, there is at least one company offering to pay people to collect the berries and willing to pay over £10 a kilo for this, in order to make herbal teas. However, I know that this company are very strict on ensuring that the foragers get permission off the landowners to do this.