According to Rodney Legg’s excellent book “Mysterious Dorset” another golden coffin myth is told about this site.
“A golden coffin is said to be buried in one of the three prehistoric round barrows on the Cowleaze, a former pasture half a mile south-east of the village (Milbourne St Andrew O.S. ref. SY811967).
Thunder and lightning begins if anyone starts to dig for it, members of the Women’s institute were told when they recorded village folklore in the 1930s.
These barrows don’t appear on multimap at the co-ordinates given , however they do appear on magic in roughly the right place . I must go and have a look at them.