I've never heard of this, but it sounds interesting.
Something of related interest would probably be the UK's Portable Antiquities Scheme:
From their website:
"The Portable Antiquities Scheme is a voluntary scheme to record archaeological objects found by members of the public in England and Wales. Every year many thousands of objects are discovered, many of these by metal-detector users, but also by people whilst out walking, gardening or going about their daily work. Such discoveries offer an important source for understanding our past."
http://www.finds.org.uk/ 
