“It is believed that the almost total absence of coins from the recent excavations (1962-3) was largely due to the long-standing custom for the local children to search there for any coins which Wayland might have overlooked. (Disbury, D. 1968. History of Ashbury, II).”
From
Notes on the Folklore of Prehistoric Sites in Britain
L. V. Grinsell
Folklore, Vol. 90, No. 1. (1979), pp. 66-70.
Would excavators really have been expecting to find many coins anyway?!