[wideawake]

It seems most equitable that the money should belong to his heirs.

What if there were multiple owners or multiple tenants? What if the hidden money was originally stolen from an enterprise that no longer exists and has no successors or assigns? Or if it is the proceeds from bootlegging or other criminal activities?

It's very difficult to prove that the money was put there by any specific person and whether the concealer, and therefore his estate, had a right to it.

There is also a common law tradition regarding possession.

the treasure trove belongs to the finder, not the property owner

Inside one's own home?

If we invited a couple over for dinner and the wife noticed that a yardsale end table buried under a bunch of tarps and tools in my garage was, unbeknownst to me, an incredibly rare antique that could fetch hundreds of thousands of dollars - could she just grab up the end table, run out to the driveway, and put it in her trunk and drive away with it?

That seems highly suspect.

[Publius Valerius]

It's very difficult to prove that the money was put there by any specific person and whether the concealer, and therefore his estate, had a right to it.

It would certainly be the burden of the heirs to demonstrate that they were the true owners. But if the heirs can make that demonstration, then I'm OK with them getting the money.

If we invited a couple over for dinner and the wife noticed that a yardsale end table buried under a bunch of tarps and tools in my garage was, unbeknownst to me, an incredibly rare antique that could fetch hundreds of thousands of dollars - could she just grab up the end table, run out to the driveway, and put it in her trunk and drive away with it?

No, because that property wouldn't be lost, mislaid, abandoned, or a treasure trove. Let's say, though, that you invited the couple over to your house and they were out walking in your backyard and, while walking, found a diamond engagement ring that did not belong to you or your wife. Under common law, your guests would be entitled to possession of the ring against the world but for the true owner.

The general rules are the lost, abandoned, and treasure trove property belong to the finder unless the true owner reappears. Mislaid property belongs to the property owner unless the true owner reappears.