Since there’s an interest in the tax implications, I’ll weigh in with my thoughts.
The spouse does get a basis step up on the date the spouse dies. Even in a community property state.
You can read more here if you are inclined:
https://www.thetaxadviser.com/issues...ms-abound.html
But the spouse died several years ago, before the COVID boom. So let’s say he died in 2016. Fair market value on that date would be the new basis. The surviving spouse then holds for several years before selling. In this case, there would definitely be a taxable gain, because the cardboard has increased in value by a lot in the interim.
The good news is that the federal tax rate is probably 28%, but maybe higher if the NIIT applies. Plus state and local tax, natch.