An excerpt from the California Civil Code, which may or may not apply within Joshua Tree National Park depending on whether the federal enclave doctrine is applicable, is reproduced below. I think all states have similar laws, although the details vary.
36 CFR 2.22, which is applicable within JTNP, states that property may not be left unattended for more than 24 hours (except under a special use permit or as a backcountry cache, as modified by JTNP rules). By implication, property may be left for periods of less than 24 hours without violating park rules. I point that out since, in other threads addressing this issue, the claim has been made that hanging draws are abandoned property under local law or regulation. Of course, even if hanging draws do violate a local law or regulation regarding abandoned property, that creates a right of law enforcement or park personnel to take charge of the property--not a right of any person to take the property (duh--just because you park your car in a two-hour zone for three hours doesn't mean I can take it).
That same regulation also requires found property to be turned into the Superintendent of the Park.
- ******************************************
2080. Any person who finds a thing lost is not bound to take charge
of it, unless the person is otherwise required to do so by contract
or law, but when the person does take charge of it he or she is
thenceforward a depositary for the owner, with the rights and
obligations of a depositary for hire. Any person or any public or
private entity that finds and takes possession of any money, goods,
things in action, or other personal property, or saves any domestic
animal from harm, neglect, drowning, or starvation, shall, within a
reasonable time, inform the owner, if known, and make restitution
without compensation, except a reasonable charge for saving and
taking care of the property. Any person who takes possession of a
live domestic animal shall provide for humane treatment of the
animal.
2080.1. (a) If the owner is unknown or has not claimed the
property, the person saving or finding the property shall, if the
property is of the value of one hundred dollars ($100) or more,
within a reasonable time turn the property over to the police
department of the city or city and county, if found therein, or to
the sheriff's department of the county if found outside of city
limits, and shall make an affidavit, stating when and where he or she
found or saved the property, particularly describing it. If the
property was saved, the affidavit shall state:
(1) From what and how it was saved.
(2) Whether the owner of the property is known to the affiant.
(3) That the affiant has not secreted, withheld, or disposed of
any part of the property.
(b) The police department or the sheriff's department shall notify
the owner, if his or her identity is reasonably ascertainable, that
it possesses the property and where it may be claimed. The police
department or sheriff's department may require payment by the owner
of a reasonable charge to defray costs of storage and care of the
property.
2080.2. If the owner appears within 90 days, after receipt of the
property by the police department or sheriff's department, proves his
ownership of the property, and pays all reasonable charges, the
police department or sheriff's department shall restore the property
to him.
2080.3. (a) If the reported value of the property is two hundred
fifty dollars ($250) or more and no owner appears and proves his or
her ownership of the property within 90 days, the police department
or sheriff's department shall cause notice of the property to be
published at least once in a newspaper of general circulation. If,
after seven days following the first publication of the notice, no
owner appears and proves his or her ownership of the property and the
person who found or saved the property pays the cost of the
publication, the title shall vest in the person who found or saved
the property unless the property was found in the course of
employment by an employee of any public agency, in which case the
property shall be sold at public auction. Title to the property shall
not vest in the person who found or saved the property or in the
successful bidder at the public auction unless the cost of
publication is first paid to the city, county, or city and county
whose police or sheriff's department caused the notice to be
published.
(b) If the reported value of the property is less than two hundred
fifty dollars ($250) and no owner appears and proves his or her
ownership of the property within 90 days, the title shall vest in the
person who found or saved the property, unless the property was
found in the course of employment by an employee of any public
agency, in which case the property shall be sold at public auction.