Jamie Mitchell offered to eat the illicit ham on the spot, but the border official was having none of it.

"I said, 'Can I just have a couple pieces of it now?' and she said, 'I really can't let you do that,' " said the Washington lawyer, recalling his tussle with customs regulations at Philadelphia International Airport last year.

"But she was very nice for someone who was taking $60 worth of ham from me," he said of the Spanish jamon Iberico he'd been so seduced by during his vacation he had to bring some back. Or at least try.

Hijacked hams, seized sausages, confiscated confits. On a typical day last year, U.S. Customs and Border Protection processed 1.13 million people entering the U.S., and seized nearly 4,300 prohibited plant or animal items.

And during the summer, when travel peaks and Americans stampede to Europe, you can expect your friendly customs officers to be especially vigilant.

The rules for what you can — and can't — stuff into your suitcase are so complicated that even conscientious travelers like Mitchell — who declared the ham and was initially waved though — might have trouble.

Created by the Department of Agriculture and enforced by Customs and Border Protection, the rules allow some things that seem dicey and flag others you might not even think about.

The result is a bit of a regulatory roller coaster.

Fungus routed from the ground by pigs in France? Load up. Basil plant from your grandmother's garden in Italy? Pack it up (just shake off the soil)! Kangaroo jerky from Australia? Bon appetit.

But don't even think about canned corned beef from Dublin or smoky Spanish chorizo. And foie gras, even cooked and canned? At your peril.

In general, baked goods, candy and chocolate are all fine to bring into the U.S. Condiments — oil, vinegar, mustard, pickles, syrups, honey, jelly — also fine.

Cheese is trickier, with hard varieties such as parmesan and cheddar allowed, but soft, fresh or runny varieties, such as brie, burrata and ricotta — big no-nos.

Fruits and vegetables generally are prohibited or require special certificates, unless you can prove they were grown in and came directly from Canada. Except potatoes. No Canadian potatoes, which have suffered disease outbreaks.

Fresh meat generally is forbidden. No steaks, no chops, no sausage. Unless it comes from New Zealand.

Cured meats — that's your Serrano, Parma and Iberico hams, plus Hungarian salami and other delicacies — are almost always forbidden. Unless they come from particular, preapproved production facilities.

So how does a traveler navigate all this?

"As a rule of thumb it's best not to bring it in or to at least declare it at the port of entry," says USDA spokeswoman Melissa O'Dell. Fines start around $300 and can climb to $10,000.

If there's something specific you know you will want to bring back, you can research it in the various manuals or on government Web sites. But it may take several phone calls before you get a clear answer about how, or whether, you can bring the item back. In some cases you may need a permit or certificate.

The authorities aren't just being dinner party poopers. And they're not actually worried about whether you get sick.

They're concerned with protecting the U.S. food supply. Contaminated meat can put U.S. livestock at risk of mad cow disease, foot and mouth disease, swine fever, avian flu and other illnesses that can enter the food supply through garbage feeding and other means. Plants may harbor pests that could decimate whole crops.

So the regulations are based on the disease conditions in the country the product is from. Beef in any form is not allowed from Europe, Oman or Israel, all classified as areas with bovine spongiform encephalopathy, or mad cow disease. Canned beef bulgogi from Korea, however, is fine. Korea is classified as free of mad cow.

Spain and Italy are recognized as countries with swine disease, so in general no ham because curing methods don't always kill the disease. Parts of France have been designated as bird flu zones, so no foie gras.

Border protection officials insist there is no personal discretion involved when it comes to fines or confiscation, yet sometimes things do get through.

Atlanta-based chef John Wilson, who spends several months a year in Europe, once stuffed his suitcase with pecorino and parmesan cheeses, dried mushrooms, olive oil, vinegar and 12 bottles of wine.

"The inspector said, 'Let's nail this guy,' and the agriculture guy said no, I was OK," Wilson says. Except for the wine. "I told him I would pay the taxes, but they said, 'Put it back in your luggage. It's not worth the paperwork.' "

And if you do try to sneak something past, chances are it won't be the most shocking item officials have seen.

For Maurine Bell, port veterinarian at Chicago's O'Hare International Airport during the 1990s, that would be the whole goat she once found stuffed in a passenger's luggage.

"The gentleman was from Greece and he was bringing it in for his daughter's wedding," she says. "We took the goat. And the suitcase, too."