This story might be the most "phantom" What If? Phantom post I've shared... While reading a newspaper article about two 1930 United States ("US") commemorative half dollar proposals -
1930 Massachusetts Bay Colony Tercentenary and
1930 Gadsden Purchase - I came upon a reference to a proposal being floated in Portland, Oregon to seek a US commemorative coin to use as a fund raiser to help establish a local museum and purchase an old US Post Office building. (I did not come across the specifics of the museum in question, but a Portland Museum of Natural History was "in the news" at the time, so a connection with such is plausible.)
Circa 1930, the US Post Office Department decided to move out of its then-current location in Portland, Oregon and build a new, more modern (albeit less character-rich) mail processing facility; it completed its relocation in 1934. The imposing original structure was constructed in 1868 using marble (vs. granite) in the Greek Revival architectural style.
Portland, Oregon Post Office and US Courthouse - Circa 1868
(Image Source: Library of Congress, Prints and Photographs Division. Public Domain.)I didn't find details regarding the coin proposal (e.g., number of coins to be requested, name of sponsor, etc.), but did note that net proceeds from sales of the coins were to be used to secure the old Post Office for use as a to-be-established museum.
The Federal Government did not sell the building, however, choosing instead to use it as office space for several decades after - it did so into the 1960s. The building was demolished in 1965 to make room for a parking facility for Federal employees.
The "local" nature of the coin would definitely have presented an obstacle to the coin proposal's passage if it had made its way to Congress (especially in light of Hoover's veto of the Gadsden Purchase coin bill), but it appears it lost momentum/support before such a legislative introduction. (Perhaps the Government's decision not to sell the building?)
For other of my topics on commemorative coins and medals, including more What If? and What If? Phantom stories, see:
Commems Collection.