If it has the same profile, thickness and weight as a 20p, then it is a blank that got through. It should be flat on both sides as the relief is made by the dies. They usually sell for a few pounds at most, so there isn't a fortune to be made, but it's still a nice thing to have. Basically Hannah, you can group 'weird coins' into groups : • misstrikes and errors (which Rob has identified yours as) - these are collected by some, but even if you don't sell it for a modest sum, it is worth keeping aside as a curio • counterfeits - these might be created to fool slot machines, or like so many current £1 coins, to pass off as a genuine coin; some are historic : a lot of early 19th Century silver was counterfeited in copper and given a thin wash of silver, and these are now quite collectable in their own right. • forgeries - these are valuable coins which have been faked to fool collectors, and which are our biggest headache • tokens - produced to meet a shortage of small change (e.g. late 18th Century), or gambling chips, or even for political reasons • coins that have been 'tooled' or defaced after being taken from circulation - engraved love tokens in the 19th Century, or just worn on a necklace; some are interesting and collectable without being particularly valuable, others are near worthless, e.g. modern coins with initials engraved • coins that have acquired a patina or other unnatural tone - e.g. green from being buried in the ground, or turned into wafers from being immersed in acidI'm sure there's other groupings I've missed - it's worth a whole study in itself! I have a love token i thiink, says MV in very nice lettering, worth its silver at least Acid? What a nasty thing to place a little coin in!!!! Hummph >