https://www.merriam-webster.com/dictionary/fungible

Nothing to do with mushrooms (or badgers or snakes). And also nothing to do with a Runcible Spoon. Of course, a runcible spoon could be fungible, providing it is identical to another. Highly unlikely really, as there is argument that money itself is not totally fungible Re London Wine Co (Shippers) Ltd [1986] and principles considered later in https://www.supremecourt.uk/cases/docs/uksc-2010-0194-judgment.pdf

fungible

adjectivefun·​gi·​ble | \ ˈfən-jə-bəl  \

Definition of fungible

 (Entry 1 of 2)1: being something (such as money or a commodity) of such a nature that one part or quantity may be replaced by another equal part or quantity in paying a debt or settling an accountOil, wheat, and lumber are fungible commodities.fungible goods2: capable of mutual substitution : INTERCHANGEABLE… the court’s postulate that male and female jurors must be regarded as fungible— George Will3: readily changeable to adapt to new situations : FLEXIBLEManagers typically use more than a hundred different lineups over the course of the season. Batting orders are so fungible that few players last long in one spot.— Tom Verducci

fungiblenoun

Definition of fungible (Entry 2 of 2): something that is fungible (see FUNGIBLE entry 1 sense 1) : a good one part or quantity of which can be substituted for another of equal value in satisfying an obligation —usually used in pluralFungibles may be valued by weight or measure.