In the mid-2010s, The American Mint, launched a medal series under the banner "National Symbols." In each case, the subject of an included medal presented an official symbol of the United States ("US") as legislated by the US Congress. In none of the cases did Congress authorize the striking of a commemorative coin or medal. As a result, no coins/medals were produced by the US Mint - any such commemorative pieces would have to come from the private sector. Hence, The American Mint. I categorize these medals as US commemorative "adjacent".The first medal of the
National Symbols series recognized the North American Bison as the official US Mammal. Congress' effort regarding this designation began in May 2012 during the 112th Congress. Efforts in the 112th and 113th Congresses stalled, but success was found in the 114th Congress via a bill introduced by William Lacy (D-MO).
The bill included an extensive "Findings" section that outlined the long-term historical and cultural importance of the North American bison. The section began with:
"(1) bison are considered a historical symbol of the United States;
(2) bison were integrally linked with the economic and spiritual lives of many Indian tribes through trade and sacred ceremonies." Other Findings reviewed the Bison's near extinction and the conservation efforts that rescued it.
Following the Findings, the bill stated:
"The mammal commonly known as the "North American bison" is adopted as the national mammal of the United States."The bill was signed into law by US President Barack Obama. With that, it was official.
Here is the medal from The American Mint:
North American Bison - National Symbols Series

The medal is silver-plated copper, has a diameter of 40 millimeters and features a Proof finish.
Note: I've been in contact with The American Mint. The National Symbols medal series is apparently still available - $79.95 per medal. I purchased mine via ebay for $10 - a price point I was comfortable with considering the medal's design and technical quality.For other of my posts about commemorative coins and medals, see:
Commems Collection