My wife bit into a coffee cake at work the other day, expecting the typical office potluck flavor. She was surprised, she said, to taste a distinctive note reminding her of her childhood backyard in northwest Indiana.

It's a taste that brings back all kinds of memories for native Midwesterners like her everywhere: black walnuts.

She was excited. I stared blankly. Black walnuts? People really eat those green balls that are underfoot all fall?

Of course they do, but a rum cake-eating Italian kid from southern Connecticut (that would be me) doesn't know that. The trees don't grow there.

A couple of days later, she came home with a bag of walnuts her supervisor had harvested from her yard and cracked one for me to try. I didn't have to try many. These things announce themselves in a big way.

If you have never had a black walnut, you probably right now have the flavor of an English walnut, intensified slightly, on your mind's palate.

Wrong.

Black walnuts are the un-walnut. They taste of the earth: musty, bittersweet and thick. They come storming into your taste buds. If they had a soundtrack, it'd be "The Imperial March (Darth Vader's Theme)."

That's their appeal. Black walnuts taste like something you worked hard to get — like you did a whole season of farming in just a couple of hours.

But they are divisive. A pastry chef I know gave them a try and couldn't get past the "oily, unripe aftertaste." I admit, they still have a raw taste even when toasted, which mellows them some.

People often assume that just because something is edible, hunter-gatherers in our prehistoric past automatically ate it no matter how hard it was to eat. Not true for black walnuts, which are native to 15 or so states from Nebraska to Virginia and from Michigan to Mississippi.

Mark Schurr, an associate professor of anthropology at the University of Notre Dame, says that because black walnuts were much harder to process than, say, hickory nuts or acorns, they were often left alone. Schurr, who also studies prehistoric nutrition, adds that black walnuts were on the ground in the fall, when more easily harvested foods were abundant.

Black walnut meats are much smaller than other nuts and are difficult to pick out of the shell, which grows into the meat more than does the shell of English walnuts (which are actually from eastern Europe and Asia). That's why you only see black walnuts chopped and never in more presentable-looking halves.

Also, black walnut meats are about two-thirds oil. The oil contains the antioxidant alpha-linolenic acid, which is one of the celebrated omega-3s we always hear about, according to Peter Pribis, assistant professor of nutrition at Andrews University in Berrien Springs, Mich. Pribis is studying whether English walnuts, which are similarly endowed, can improve cognition. (If they can, then after all I've eaten for this story, I should be able to move objects with my mind.)

One reason people let black walnuts lie is that they are literally a tough nut to crack. Aside from using a huller, people find other ways to break them: a rock (hurt hands; swear a lot); a hammer (drill hole in board; whack nut through hole; make black, inky mess); a car (sweet). One guy I work with put them in a cement mixer with rocks for an hour. It made a mess, but it worked well.

Once the nuts are hulled, they need to dry for a few weeks before cracking. A rule of thumb is to leave them until you can hear the nut rattle when you shake it.

That's a lot of work, but people do it. And there's a good reason for it. Ask Midwesterners. They'll tell you that nobody made a better "(Name a state here) Black Walnut Cake" than their grandma.

That's the beauty of a native food. Everyone claims it as his or her own. Officially, the eastern, or American, black walnut is the state tree nut of Missouri. That's because most nuts that people pick up off the ground by the truck- and trailerful (seriously, a guy here showed up with a trailer full of black walnuts in buckets, barrels, bags and the gutted metal case of a Sears battery charger) are sent to Missouri's Hammons Products Co. Hammons has been processing walnuts since the 1940s and handles about all the black walnuts you see in stores.

If you live in one of the states where black walnuts grow, you can probably get local nuts at a farmers market. Load up: They keep for a year in refrigeration and up to two years in the freezer. If you live where the trees don't grow, it's easy enough this time of year to find black walnuts under the Hammons label at supermarket chains including Kroger and Wal-Mart. At other times of year, black walnuts can be found under stores' private labels or other national brand names. Either way, the nuts most likely came from Hammons.

I'm still working out whether I like black walnut. To a lot of people, it's a signature taste of fall, and around here, people put the nuts in cakes, cookies and stuffing, or they buy black walnut ice cream from the Amish. But like them or not, if you use them, your dish will get noticed. Just be sure to warn the New Englanders first.

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