I think your button is a fashion one from the mid 20th century.. The main clue being the missing back. Here's a link to one very similar to yours listed under the fashion heading at the Waterbury web site.
The UK's Colchester Treasure Hunters website's button-ID section shows one extremely similar to yours (the anchor is very slightly different) and identifies it as a "Generic" 1900s UK Merchant Navy button. Navy buttons