A treasure trove is an amount of money or coin, gold, silver, plate, or bullion found hidden underground or in places such as cellars or attics, where the treasure seems old enough for it to be presumed that the true owner is dead and the heirs undiscoverable. An archeological find of a treasure trove is known as a hoard. The legal definition of what constitutes a treasure trove and its treatment under law vary considerably from country to country, and from era to era.

The term is also often used metaphorically. Collections of articles published as a book are often titled Treasure Trove, as in A Treasure Trove of Science. This was especially fashionable for titles of children's books in the early-and mid-20th century.

The law of treasure trove in the United States varies from state to state, but certain general conclusions may be drawn. To be a treasure trove, an object must be of gold or silver. Paper money is also deemed to be a treasure trove since it previously represented gold or silver. On the same reasoning, it might be imagined that coins and tokens in metals other than gold or silver are also included, but this has yet to be clearly established. The object must have been concealed for long enough so it is unlikely that the true owner will reappear to claim it. The consensus appears to be that the object must be at least a few decades old.

A majority of state courts, including those of Arkansas, Connecticut, Delaware, Georgia, Indiana, Iowa, Maine, Maryland, New York, Ohio, Oregon and Wisconsin, have ruled that the finder of the treasure trove is entitled to it. The theory is that the English monarch's claim to treasure trove was based on a statutory enactment which replaced the finder's original right. When this statute was not re-enacted in the United States after its independence, the right to treasure trove reverted to the finder.

In Idaho and Tennessee courts have decided that the treasure trove belongs to the owner of the place where it was found, the rationale being to avoid rewarding trespassers. In one Pennsylvania case, a lower court ruled that the common law did not vest treasure trove in the finder but in the sovereign, and awarded a find of $92,800 cash to the state. However, this judgment was reversed by the Supreme Court of Pennsylvania on the basis that it had not yet been decided if the law of treasure trove was part of Pennsylvania law. The Supreme Court deliberately refrained from deciding the issue.

Finds of money and lost property are dealt with by other states through legislation. These statutes usually require finders to report their finds to the police and transfer to their custody the objects. The police then advertise the finds to try to locate their true owner. If the objects remain unclaimed for a specified period of time, title in them vests in the finders. New Jersey vests buried or hidden property in the landowner, Indiana in the county, Vermont in the town, and Maine in the township and the finder equally. In Louisiana, French codes have been followed, so half of a found object goes to the finder and the other half to the landowner. The position in Puerto Rico, the laws of which are based on civil law, is similar.

Finders who are trespassers generally lose all their rights to finds, unless the trespass is regarded as "technical or trivial".