President Herbert Hoover issued the first Presidential Veto of a US commemorative coin bill when he followed the wishes of the Treasury Department and blocked the Gadsden Purchase 75th Anniversary Half Dollar from being struck/issued. (You can read about it here:
What If? 1930 Gadsden Purchase.
This was not the first time the Treasury Department had made its objections to US commemorative coins known, however. Of course, the 1925 Norse-American Centennial Medal is a well-known example of the Treasury exerting its influence to transition a potential coin bill to a medal bill (read more here:
1925 Norse-American Centennial Medal - Origin Story.)
Less well-known are the efforts of the Treasury to thwart the issue of the 1925 California Statehood 75th Anniversary, the Fort Vancouver Centennial and the Battle of Bennington / Vermont Independence Sesquicentennial half dollars. In 1925, Secretary of the Treasury Andrew Mellon wrote to President Calvin Coolidge regarding the above bills in an attempt to get him to veto them.
In his letter, Mellon referred to previously-approved commemorative coin proposals and stated:
In other words, the Federal Government is permitting its coinage system to be commercialized for the profit of any celebration, whether national in scope or not...I feel that even for an anniversary of national significance the Treasury should not be asked to debauch its currency system, either of coins or paper.Secretary Mellon continued:
Each case is precedent for the next case, and we must draw some limit to the diversion of our currency from its legitimate purpose as a means of payment by the general public for its business transactions, to a means of profit to particular bodies.The Treasury Department didn't win this round, as all three of the commemorative half dollars were approved by Congress and signed into law by Coolidge. (Coolidge did not veto any commemorative coin bill(s) presented to him.) The stage was set, however, for a series of Treasury vs. the President/Congress "battles" regarding US commemorative coins - and they would play out in the decades that followed.
1925 California 75th Anniversary of Statehood Half Dollar
1925 Fort Vancouver Centennial Half Dollar
1926 Battle of Bennington / Vermont Independence Sesquicentennial Half Dollar

For other of my posts about commemorative coins and medals, including other Quick Bits stories, see:
Commems Collection.