Albert Edward, Prince of Wales, married Alexandra Caroline Maria Charlotte Louise Julia of Denmark in 1863. They became King and Queen of England when Edward's mother, Queen Victoria, died in 1901.
Numerous medals were struck in honor of the royal couple. The one in our picture is from 1907 on the occasion of the opening of Queen Alexandra Dock in Cardiff. There are many more such medals, and an Internet search of 'King Edward VII coronation medal' draws many hits. There is a comprehensive collection on the Alexandra Park web site.
Medals like this usually sell retail for $20 to $40 US dollars, depending on condition. The one in our picture is in good shape, with only a few small stains on the reverse side. This should sell on eBay for $20 or so. If you have one to sell to a dealer, figure an offer in the $10 range.