[rainbowzootsuit]

In that situation, the inability to eat it or shoot something with it is probably going to make gold/silver pretty close to worthless as well until society re-exists.

Even if the US government ceases to exist, the features of non reproducibility built into cash dollars (watermarks, intaglio printing) would still exist although they won't be as ultimately durable into the future as an element. At least you can also use them as fire starters.

[jpdb]

Paper money has a lower bound of material value equal to $(toilet paper - utility value for the comfort of toilet paper over a dollar bill) per square inch.