Speaking as a foreign national, in this post 911 world I find it hard enough to get into the US with a valid green card, and am always rather nervous about accidentally bringing fruit or suchlike contraband into the country. They don't like it if you bring fruit, and on several occasions at Minneapolis airport I've been taken aside and quizzed about whether I have any fruit on my person, or a cheese sandwich.
They seem to be loosening up on other things though:
Massachusetts lawmakers on Thursday called for a closer look at border security after customs officials allowed a man carrying a sword, a hatchet, brass knuckles and a chain saw stained with what appeared to be blood to cross the U.S.-Canadian border. Two days after being allowed into the United States in late April, Gregory Despres, 22, was arrested in Massachusetts in connection with the beheading of his elderly neighbor and the stabbing death of his wife in the New Brunswick town of Minto.
(It seems that the US customs/immigration people are saying that because he was a naturalised American, they had to wave him through. I bet they could have stopped him if only he'd had an apple.)