A lot of clubs help charities; my local club gave over £3,000 to the Air Ambulance recently. The best way is to get a club to organise a one day dig event together with a local landowner ( who may already have a chosen charity in mind ). The profits from the day the go to the charities. Hundreds of thousands of pounds are already being donated by the many Metal Detecting and related societies.
Clubs often get asked to help find missing jewellery even lighters and medals. One such group can be found at https://www.facebook.com/groups/ringandjewelryfinders/
There are several benefits to Farmers offered by Metal Detecting on their land:
To remove waste
Remove sharp or large objects that might hurt their livestock or machinery
Help them learn more about their land and its history
To find lost articles
To discourage unwanted visitors like fly-tippers
Another pair of eyes to alert them about damaged fences or animals in distress
To possibly make them rich, if they have a 50:50 finder’s agreement!