Upon leaving the US, ask a US Customs representative for a fact sheet detailing restrictions on what you may bring back into the country upon your return. There are some restrictions on what you may purchase, and import, without paying duties; as well as restrictions on importation of alcoholic beverages. Bringing back most foodstuffs and plant material is forbidden.
Please take my advice: never, ever try to “sneak” anything by US Customs representatives. Tally up your purchases and itemize them on the form you’ll be given on your flight home; and pay your duties.