Collector Coin sold as part of the Tak Kickstarter campaign. The Collector Coin is to be used as a marker of the game board center when playing Tak on a virtual board (i.e. without a board).
Description from the publisher:
About the Coin: Cheapass Games makes a new collector coin with each Kickstarter campaign. They are usually round, but this coin will be a 36 mm square (approx. 42" on the diagonal). This coin is ideal as a centerpiece, allowing you to play Tak without a board!