A coffee stained napkin started it all.

Drawn to scale, the backyard version of Boston’s baseball diamond penned on that napkin 17 years ago became a reality in 2001, transforming a once overgrown 11-acre spot into a Wiffle ball haven. Today, Essex Jct. knows it as Little Fenway.

Soon came the Chicago Cubs-inspired Little Wrigley in 2007 and Iowa’s Little Field of Dreams in 2014.

Over the last 16 years, the complex and its owner, Pat O’Connor, have raised over $4.6 million for the Travis Roy Foundation, which purchased all three fields and O’Connor’s home in January. While O’Connor wasn’t actively searching to sell, he said he’s excited to see what’s to come.

“What makes this place special is the commitment to the greater good and the community,” O’Connor said.

TOP: Pat O’Connor stands on the mound of Essex Jct.’s Little Fenway, one of three fields the avid baseball fan built in his backyard that hosts massive fundraising events. ABOVE: To portray an authentic Chicago feel, ivy grows on Little Wrigley’s brick backdrop.

Part of it, too, is O’Connor’s attention to detail.

At Little Fenway, a towering Green Monster extends from the left field foul pole. On the scoreboard, Morse code traces the initials of two former Red Sox owners, Tom and Jean Yawkey. In the bullpen, tomato plants call back to 1990s pitching coach John Cumberland’s cure for boredom during long Sox games.

The green paint, now coined by Benjamin Moore as Green Monster Green, wasn’t available during the field’s construction. Dedicated to an authentic portrayal, a sidekick of O’Connor’s did what any true fan would do: get his Fenway fix in Boston, secretly scraping a piece of paint off the dugout.

Another friend filled a small vial with Fenway dirt. O’Connor searched for its color equivalent for Little Fenway.

“It was almost a perfect match,” he said with a sly grin earlier this week as he circled behind the Green Monster, down a path to Little Wrigley.

There, a backdrop of an ivy-covered wall emanated true Wrigley style. Among the stenciled bricks is one original, shipped directly from Chicago.

O’Connor’s father traveled from Virginia to place the brick at the field’s first day, just as he had to throw the first pitch to his grandson at Little Fenway’s debut. The July 4, 2001 game was none other than Red Sox versus Yankees.

Beyond Wrigley’s right field wall is Little Field of Dreams. Every August, O’Connor transplants cornstalks along the outfield. If it wasn’t for Camel’s Hump peeking above the stalks, Wiffle-ballers might forget they weren’t in Iowa anymore.

This sense of place, O’Connor said, is what drives his hobby. The energy, though, wasn’t always as positive, he recalled.

“The project was almost dead on arrival,” he joked, remembering his team’s first day building Little Fenway.

On the Green Monster, two lines of Morse code signal the initials of former Red Sox owners Tom and Jean Yawkey. The Yawkeys are at the center of controversy over former segregation in Major League Baseball. So if Fenway takes the initials down, so will Little Fenway, founder Pat O’Connor said. “We do whatever the Red Sox do,” he said. (Photo by Kaylee Sullivan)

A couple digs in, they hit ledge but didn’t give up, instead working together to solve the unexpected pickle.

Around the same time, O’Connor inquired about a Citgo sign at the local gas station. It just so happened there was one in the back. Soon, it was placed in a tree in Fenway’s left-center field, opposite the line of retired numbers hanging beyond the Pesky Pole.

Chuckling, O’Connor remembered adjusting the sign after numerous storms. That was until he took a tumble, and needless to say, a pole now hoists the sign in left center.

Interested in O’Connor’s hometown success, the Essex Rotary invited him to speak at last week’s meeting. There, he detailed his business model, which to his surprise, is being replicated throughout the country. A Little Fenway may even pop up oversears sometime soon, he said.

The complex’s success wouldn’t be possible without the help of the hundreds of volunteers and the committee that plans the Travis Roy tourney every year, O’Connor said.

  “This story is as much about building a family as it is about building fields,” O’Connor told the Rotarians.

Numerous former Sox players have graced the fields. In 2003, a local pastor blessed Little Fenway, and the next season, the Sox broke the “Curse of the Bambino,” winning the World Series title.

But that’s just a coincidence, right? Any superstitious baseball fan wouldn’t think so.

Today, foundations like the Strike 3 Foundation, which raises money for childhood cancer, and SLAMDiabetes fundraise at the fields. The latter expressed interest in buying the property first, but O’Connor approached the Roy Foundation, his biggest stakeholder, he said.

Roy, a former Boston University hockey player, was paralyzed in his first 11 seconds of collegiate play. His foundation supports paraplegic research and adaptive equipment grants.

He said he wasn’t necessarily in the market, but when O’Connor contacted him, he couldn’t overlook the immense value the fields cultivated over the years.

“Never in [his] wildest dreams” did Roy think the trio of fields would mature into what they are today.

“It’s just been a magical place for us, and I’m excited to know the tourney will continue for years to come,” Roy said.

The foundation leased the land back to the O’Connors for the next two years, as they work through the transition. O’Connor, who owns the New Bedford Bay Sox, a summer collegiate Massachusetts baseball team, said he and his wife will move to Atlanta, where two of their three kids live.

O’Connor said his wife, Beth, a longtime Essex High School Spanish teacher, deserves a lot of credit for allowing him to convert their backyard into his own personal playground.

An old photo shows the beginning construction phase of the renowned Green Monster at Little Fenway. (Photo by Kaylee Sullivan)

“Who in their right mind would take on this upkeep?” O’Connor pondered, thinking of his home’s next tenant who will move into the “pinnacle of Wiffle ball” come June 2019.

The foundation must find a special breed like O’Connor – obsessed with detail and passionate about the greater good. Unable to bear the thought of missing out, O’Connor said he’ll attend the tourney each year.

His dedication matches that of his younger self, when he and his brother traveled in a van cross-country watching every Major League Baseball team compete.

The real kicker? O’Connor’s No. 1 team is the Los Angeles Angels. Fenway just happened to rank at the top of the duo’s favorite fields list. Other rankings of those “Diamond Days” included best hot dogs, players, ball girls and so on, he recounted.

The passion O’Connor had then is heartily evident today. Memories of his younger days at Fenway Park with family still ring strong as part of the complex’s ever-growing life.

As he rummaged through plastic bins brimmed with old photographs this week, each moment held significance: his kids dumping dirt when the Green Monster was just wooden supports protruding from the ground, or former Sox player Bernie Carbo’s visit.

As for the bigger picture, it all comes back to that napkin drawing.

“My legacy is this place,” O’Connor said. “It still has a lot of life left.”