A superb site for research of Early Medieval coin finds of the British Isles.
EMC (Corpus of Early Medieval Coin Finds) is a project based at the Fitzwilliam Museum in Cambridge that records single finds of coins dated between AD 410 and 1180. See their Contacts page for details of how to record your finds.
SCBI (Sylloge of Coins of the British Isles), which is supported by the British Academy, publishes coins in museum collections in Britain and many other parts of the world. This website provides access to about 12,000 finds in EMC and 46,000 coins in SCBI.
Checklist of Coin Hoards. The Checklist of Coin Hoards from the British Isles, c. 450-1180, maintains a comprehensive list of hoards from the Anglo-Saxon period, Norman and early Plantagenet periods.