Worse still, many graves will never be found.
She knows no one can pay her and the group of Camden County historians working with her for the painstaking research they do - often in vain - to fill in the blanks.
But in just a matter of months, their detective work has identified 24 graves, reclaiming plots in the 222-year-old cemetery that have been unmarked for generations. Each success is a victory that keeps the researchers hard at work.
It often starts with a vague memory shared by a family member, a snippet in a county history book, or a brief obituary in a newspaper or old church bulletin. That was the case for a 3-year-old child who died of Spanish flu in 1918, when death certificates weren't required.
A family member recalled that the toddler was buried at the foot of a sago palm near the rest of the Frohock family plots in the cemetery's 7-acre "old section." It took a team effort to prove him right. First, cemetery director Jerry Sizemore used a rod to probe the ground around the small palm. He eventually hit what felt like solid stone. Then caretaker Tammy Walker went to work, carefully digging through roots and dirt until she uncovered the tiny grave. Westberry marked the site. One more piece of St. Marys history is back from obscurity.
"I guess it's the mama in me that makes me do this," she said after a visit to the site one recent day. "Somebody loved that child, and they didn't want their baby to be forgotten even if they couldn't afford a headstone."
A century ago, graves in St. Marys' only public cemetery often were marked with a simple pile of ballast stones, sea shells or shards of glass. Sometimes, families just used a pile of dirt. As time passed, vandals stole what was valuable, children moved precious markers that seemed more like toys, and countless visitors trampled the dirt piles, incorporating them into the worn paths that snake through the grounds.
Other graves were never marked at all. During the yellow fever epidemic in the 1800s, there weren't enough caskets to keep up with the piling bodies. Entire families died within days of each other, and they were buried en masse in makeshift trench-like graves.
It's no wonder that graves were forgotten, and new graves were buried on top of them. Trees sprouted sometimes in the middle of a gravesite. Stone walls and roads were built with no way to know whether the dead were below them.
Efforts to reclaim lost graves began 90 years ago.
"In 1921, they listed all the unmarked graves they knew about at the time," said county historian Eloise Bailey Thompson. "The problem was, they wrote things like, 'This person was buried under the camellia bush.' Well, now we look and we ask, 'Which one?'"
Westberry is determined to prevent that from happening again, so she's using maps and graphs to record the exact location of each grave the historians identify.
There are more than 900 unmarked graves listed in the old records, Thompson said, and she suspects there are many more beyond the records. While there is no way to name them all, she has faith that more will be identified.
The longtime historian, along with Ann Stoddard and Mary Jane Stevens, has spent years, literally decades, researching the cemetery's lost history, walking amid the towering oaks with descendents of those buried long ago.
"It takes the efforts of a lot of older people walking through the cemetery; that's the only way to do it," Thompson said. "Now, I'm one of the older people. After another generation, nobody would know these things, and that history would be lost."
Perhaps more than any other historic site in St. Marys, Oak Grove Cemetery is a silent testimony to the rich past not only of the city, but of Camden County as a whole. The founders of Kingsland and Woodbine are buried there. So are generations of Acadians, who escaped British attackers in the north and oppressive working conditions in Santo Domingo before establishing prosperous businesses in St. Marys.
There is an old stone wall dividing the sections where blacks and whites are buried, a testimony to the divisions that also existed in life. There are soldiers from every major war, including Robert Carmichael, a Confederate soldier from the Civil War. No one knew who was buried in the unmarked plots around him until just recently, when his wife and family members' burial records were uncovered in the historians' research.
Westberry has always loved history, so much so that she wrote a 700-page volume about her own family's roots. But, in her more than 20 years living in St. Marys, she'd never set foot in Oak Grove's old section until about a year ago, when she was asked to guide a tour of the cemetery. She was instantly drawn in, and soon made it her mission to recover as much history as she could about those resting in unmarked graves.
In November, the historians asked the City Council to permanently ban plot sales in the cemetery's old section. The council unanimously agreed. The only new burials allowed there will be for those who can prove their family already owns a plot.
Although Westberry sees a large turnout during the occasional tours she offers in the cemetery, Oak Grove is off the path of the typical tourist. Today, there isn't so much as a brochure available about its history. But Westberry says that will change soon.
She's on a mission to let the public know about Oak Grove, and to get more support for its preservation. She also plans to write a book about the cemetery, so - 100 years from now - perhaps a future generation of historians will have a better starting point.