Last I knew: No fruits/vegetables, meat, firewood and as it was mentioned earlier pets need proper documentation. Also, pet food needs to be in original packaging.
Not too sure about alcohol.
I think a lot of it depends on the customs officer and whether or not he's in a good mood....
My in laws travel to the states often and one time they questioned the dogs documentation but did not ask about any meat (he had steaks in fridge for dinner that night) and the next time he crossed they didn't care about his dog but confiscated his steaks.... I bet that officer enjoyed his dinner that night