Berryville, Virginia (CNN) -- Travis and Joyce Miller might have the most fragrant garage in the Shenandoah Valley.
The heady scent of hickory wood wafts from their rural home on Virginia's busy Route 7, catching the attention of hungry commuters who might expect to find a grandma tending the hearth or, even better, a pitmaster roasting a hog on the side of the road.
What's cooking, though, is something a little bit sweeter (sorry, grandma): It's Falling Bark Farm hickory syrup.
Never heard of hickory syrup? Neither had the Millers until a few years ago when a chance Internet search turned up mentions of it.
In 2011, they showed up to the farmers market in nearby Purcellville, Virginia, with 48 bottles of their new science project -- "which we felt was a little bit risky," Travis says.
The risk paid off. The couple aim to sell 30,000 units this year.
The Millers credit tapping into the market at the right time with all the right buzzwords: foraged, locally sourced and, most of all, unique.
They're the first to admit they didn't have a divine syrup destiny; they're just retirees looking to get by via trial and error -- a challenge that Americans of all ages face regularly.
"Everybody out there is looking for something new," Travis says. "The difficulty is not necessarily producing the product, it's about marketing the product."
The Millers are among a dozen or so hickory syrup producers nationwide; in comparison, the maple syrup industry produced 3.17 million gallons in 2014, according to the U.S. Department of Agriculture.
The Millers have built their business by intriguing the average consumer, who often associates the flavor of syrup strictly with maple or "pancake syrup" poured from a character-shaped bottle.
"We say, 'You know what, if you just taste it. Just taste the hickory, we just want you to have the hickory experience. You don't have to buy it,' " Joyce says. They find that the flavor is all it takes to win over new customers -- not to mention the loyal following of Washington-area chefs who appreciate the syrup's smoky, earthy undertones.
"We don't say it's better or worse than maple; it's just a different culinary experience," she says. The sugar content is similar to that of maple syrup, but the intensity of the sweetness is not there, Travis adds, which is why they suggest use in meat glazes or even cocktails.
As the name suggests, hickory syrup is made from the bark of hickory trees -- shagbark hickory, to be exact.
Instead of boiling down tapped tree sap like maple or birch syrup makers would, the Millers craft their product by extracting flavors from the actual bark that's been foraged from the forest floor. They scrub the bark clean, roast it over an open flame and then boil it with turbinado sugar to form a syrup.
Throughout the Millers' 33-year marriage, the couple have always looked to their hands -- and the land around them -- as a means of making a living. They grow and eat their own produce, hunt and cook their own game, and have even built most of their houses from the ground up.
Joyce says the initial plan was that if they could work a weekend producing syrup and make the same amount of money Travis was earning at his odd retirement jobs, they'd take that idea to the next level and pursue it full time.
Three years later, the notion seems to have stuck.
"I think the family that works together, stays together," Travis says.
At first, they experimented with compound butters and smoked salts. The smoking led them to looking into different woods to smoke -- from there they branched into hickory.
"And then syrup just started happening," Joyce says. "And it's continued to happen. We're going to follow it wherever it takes us."
They individually bottle each unit in their home using a Hamilton Beach coffee urn, and drive orders to the post office in their truck with a license plate that reads, "SRP HPNS" (syrup happens).
People in their small rural community know them as the hickory syrup folks, and have started to chip in by letting the couple stop by and pick up any naturally shedding bark off their property. Oftentimes, they come home to find bundles of hickory bark on their front porch like a basket of fresh baked goods from a new neighbor.
"We just try to do the right thing," Joyce says. "I guess maybe all that's karma. It's come back around and starting to pay off."
An 8-ounce bottle retails for around $9.99, and the syrup is available nationwide in retailers such as Whole Foods as well as in Falling Bark Farm's online store.
"We don't want to get too big, too fast, kind of like the cupcake industry," Joyce jokes. "We're just taking it a step at a time."
Besides, it's just the two of them producing all the sticky stuff.
"We're just two simple senior citizens making syrup," Joyce says.
For the Millers, at the moment, money really does grow on trees.