Many collectors of the modern US commemorative coin series are familiar with the $5 gold coin (i.e., half eagle) issued in 1997 in honor of President Franklin Delano Roosevelt. I've previously discussed the individual coin here
1997 FDR Gold Half Eagle and the FDR Coin and Stamp Set here
1997 FDR Coin & Stamp Set.
Before the bill for the gold coin was passed, however, other bills that called for silver FDR coins were introduced in Congress.
Efforts for an FDR commemorative coin began in October 1993 when companion bills were introduced in the House and Senate during the 103rd Congress. The bills called for up to 500,000
silver dollars to be struck using standard specifications. The Senate bill was introduced by Daniel K. Inouye (D-HI); the House bill was introduced by Hamilton Fish, Jr. (R-NY).
The proposed coin was to have a surcharge of $10 added to its issue price, to be collected by the Mint, with 50% distributed to the National Park Foundation Restricted Account to be used for ongoing support of the FDR Memorial and 50% distributed to the National Park Foundation Restricted Construction Account for use in building the FDR Memorial. Each bill was referred to the designated Committee of its chamber, but neither made it out of committee for full consideration.
Things were switched up a bit during the 104th Congress; Senator Inouye returned with a commemorative coin bill in February 1995 that called for up to 500,000
silver half dollars to be struck to mark the opening of the Franklin Delano Roosevelt Memorial in Washington, DC. The surcharges collected on the sale of each coin - $3 - were to be distributed 50/50 as outlined in Inouye's previous silver dollar bill. As with the previous bills, this one died for lack of action. (I bet a silver half dollar would have been popular with collectors!)
In June 1995, the "United States Commemorative Coin Act of 1995" was introduced, it moved away from the idea of a silver FDR coin. In addition to calling for a gold $5 coin for FDR, it also included provisions for coins commemorating the 50th anniversary of the United Nations (silver $1), the 150th anniversary of the Smithsonian Institution (gold $5), the 125th anniversary of Yellowstone National Park (silver $1) and the National Law Enforcement Officers Memorial (silver $1). Up to 100,000 gold FDR coins were included in the proposed legislation, with each to carry a surcharge of $35; proceeds were to be paid to the Franklin Delano Roosevelt Memorial Commission.
Though this bill did not get approved, all of the proposed coin programs did eventually get authorized (in some form) with the exception of the United Nations (UN) coin. I would have enjoyed a UN coin, many other countries around the world issued coins for its 50th anniversary in 1995 - it would have been nice to add a US coin to such a set considering the US' prominence in the organization's founding.
A new multi-coin bill was introduced in 1996, the "United States Commemorative Coin Act of 1996." This one included calls for coins in observance of the 150th anniversary of the death of Dolley Madison (1999, silver $1), observance of the 200th anniversary of the death of George Washington (1999, gold $5), celebration of the 275th anniversary of the birth of the first Black Revolutionary Patriot - Crispus Attucks (1998, silver $1), recognition of the 50th anniversary of the breaking of the color barrier in major league baseball by Jackie Robinson (1997, gold $5), commemoration of the 125th anniversary of Yellowstone National Park (1999, silver $1) and recognition of the sacrifices made by law enforcement officers and their families in preserving public safety via creation of the National Law Enforcement Officers Memorial (1997, silver $1). It was ultimately successful.
The 1996 bill/Act also included language for the striking of up to 100,000 FDR $5 gold commemorative coins to be issued in 1997. A total of 41,368 1997 FDR gold coins were struck (29,474 proof coins and 11,895 uncirculated). The sales price of each coin sold included a $35 surcharge that was paid to the Franklin Delano Roosevelt Memorial Commission vs. either of the Restricted Funds of the National Park Foundation.
1997 Franklin Delano Roosevelt Gold Half Eagle

So, in the end, a group of collectors who could afford/desired to purchase a gold FDR commemorative got a new $5 gold coin to add to their cabinets, but many more collectors likely would have added an FDR commemorative coin to their collection had it been a silver half dollar or silver dollar coin!
For other of my posts about commemorative coins and medals, including more What If? stories from the Classic and Modern eras, see:
Commems Collection.