Here are GENERAL REGULATIONS for all units of the National Park Service (from CFR 36.2):
The following are prohibited:
Possessing, destroying, injuring, defacing, removing, digging, or disturbing from its natural state:
(i) Living or dead wildlife or fish, or the parts or products thereof, such as antlers or nests.
(ii) Plants or the parts or products thereof.
(iii) Nonfossilized and fossilized paleontological specimens, cultural or archeological resources, or the parts thereof.
(iv) A mineral resource or cave formation or the parts thereof.
Using or possessing wood gathered from within the park area: Provided, however, that the superintendent may designate areas where dead wood on the ground may be collected for use as fuel for campfires within the park area.
Possessing, destroying, injuring, defacing, removing, digging, or disturbing a structure or its furnishing or fixtures, or other cultural or archeological resources.
Possessing or using a mineral or metal detector, magnetometer, side scan sonar, other metal detecting device, or subbottom profiler.
The following are prohibited:
(i) Gathering or possessing undesignated natural products.
(ii) Gathering or possessing natural products in violation of the size or quantity limits designated by the superintendent.
(iii) Unauthorized removal of natural products from the park area.
(iv) Gathering natural products outside of designated areas.
(v) Sale or commercial use of natural products.
This section shall not be construed as authorizing the taking, use or possession of fish, wildlife or plants for ceremonial or religious purposes, except where specifically authorized by Federal statutory law, treaty rights, or in accordance with § 2.2 or § 2.3.
Here are provisions for the National Park Service in Alaska (from CFR 36.13):
This section applies to Wrangell-St. Elias National Park & Preseve and all park areas in Alaska except Klondike Gold Rush National Historical Park, Sitka National Historical Park, the former Mt. McKinley National Park, and the former Katmai National Monument.
Gathering or collecting natural products is prohibited except as allowed by this section. For purposes of this paragraph, ''natural products'' includes living or dead fish and wildlife or parts or products thereof, plants or parts or products thereof, live or dead wood, fungi, seashells, rocks, and minerals.
Gathering or collecting, by hand and for personal use only, of the following renewable resources is permitted—
(1) Natural plant food items, including fruits, berries and mushrooms, but not including threatened or endangered species;
(2) Driftwood and uninhabited seashells;
(3) Such plant materials and minerals as are essential to the conduct of traditional ceremonies by Native Americans; and
(4) Dead wood on the ground for use as fuel for campfires within the park area.
Wrangell-St. Elias NP&P Superintendent's Compendium - 13.35(f)(1) Natural features: The collection or gathering of mushrooms for personal use is limited to two 5-gallon containers of whole, fresh mushrooms per person, per day.
The Superintendent may authorize, with or without conditions, the collection of dead standing wood in all or a portion of a park area.
Surface collection, by hand (including hand-held gold pans) and for personal recreational use only, of rocks and minerals is permitted, with the following exceptions:
(1) Collection of silver, platinum, gemstones and fossils is prohibited; and
(2) Collection methods that may result in disturbance of the ground surface, such as the use of shovels, pickaxes, sluice boxes, and dredges, are prohibited.
The Superintendent may limit the size and quantity of the natural products that may be gathered or possessed.