Earlier quoted context omitted.
Picking up someone's phone that they left at a bar and doing a teardown on it is theft. Not in a "I think this is equivalent to theft" sense; it is theft in the legal "you can be charged with theft for doing it" sense. I know this because I know this is what happened to Gawker. It is illegal to take things that other people use and appropriate them for yourself. If someone finds your phone on the street, they need to…
You can find similar laws in many states. Here is Florida's: 705.102 Reporting lost or abandoned property.— (1) Whenever any person finds any lost or abandoned property, such person shall report the description and location of the property to a law enforcement officer. ... (3) It is unlawful for any person who finds any lost or abandoned property to appropriate the same to his or her own use or to refuse to deliver t…
http://en.wikipedia.org/wiki/Lost,_mislaid,_and_abandoned_pr...
"The rights of a finder of such property are determined in part by the status in which it is found. Because these classifications have developed under the ancient and often archaic common law of England, they turn on nuanced distinctions. The general rule attaching to the three types of property may be summarized as: A finder of property acquires no rights in mislaid property, is entitled to possession of lost property against everyone except the true owner, and is entitled to keep abandoned property.[1] This rule varies by jurisdiction"
At any rate, it basically seems to boil down to what I've said, which is that unless there is a specific law in your area stating otherwise, if you lose property, you lost it, and while it may be unethical to not report it, it's generally not illegal.
Should it be? In general I'd say no, because off the top of my head, it seems the costs outweigh the benefits. And then we come to how that impacts Monsanto.
I'd say if Monsanto can't keep it's seeds out of a silo, that's Monsanto's problem and not one that needs government intervention, which is likely to be massive and onerous to other interests. It's the nature of seeds.