Here is a list of personal items you might think about before bringing them home. http://www.cbp.gov/xp/cgov/travel/vacation/kbyg/prohibited_restricted.xml These are restrictions that apply to anyone regarless of what country they are entering the US from.
Here is a link with vehicle compliance regulations http://www.cbp.gov/xp/cgov/travel/clearing/automobiles.xml
Amimals that are on the endangered spices list can not be imported or exported. Shellfish, marine animal, crustations, coral and the like MUST be declared through the US fish and wildlife service and a permit is required . Here is a quote from the code of Federal Regulations (referring to the exceptions to import declaration requirements and regarding the importation of animal fur/parts) And I quote:
(2) Wildlife products or manufactured articles that are not intended
for commercial use and are used as clothing or contained in accompanying personal baggage, except that an importer or his/her agent must file a Form 3-177 for raw or dressed furs; for raw, salted, or crusted hides or skins; and for game or game trophies; and (3) Wildlife products or manufactured articles that are not intended for commercial use and are a part of a shipment of the household effects of persons moving their residence to the United States, except that an importer or his/her agent must file a declaration
For a more intensive look at the regulations regarding import/export of animal goods follow this link http://www.fws.gov/permits/ImportExport/ImportExport.shtml
