* 84-year-old winner opts for $371 million lump sum

* Kept winning a secret for 2-1/2 weeks (Adds description of winner's house and quotes from neighbors)

By Bill Cotterell

TALLAHASSEE, Fla., June 5 (Reuters) - An 84-year-old Florida woman claimed last month's record Powerball jackpot on Wednesday and opted to take a lump-sum payment of nearly $371 million, Florida Lottery officials said.

Winner Gloria MacKenzie of Zephyrhills, central Florida, chose the lump sum rather than collecting $590.5 million in 30 annual payments, Florida Lottery Secretary Cynthia O'Connell said in a news conference at the state lottery headquarters in Tallahassee.

MacKenzie bought the only $2 ticket that matched all six winning numbers in the May 18 multistate Powerball drawing, making her the largest sole jackpot winner in U.S. lottery history.

MacKenzie wore dark sunglasses and linked arms with her son, Scott MacKenzie, as she walked through a phalanx of cameras facing straight ahead. She left the lottery office without saying anything but left behind a statement to be read by O'Connell.

MacKenzie said she and her son had an agreement to split any winnings. She bought the winning ticket at a Publix grocery store after previously buying four other tickets, her statement said.

"While in line at Publix, another lottery player was kind enough to let me go ahead of them in line to purchase the winning Quick Pick ticket," she said.

"We are grateful for this blessing of winning the Florida Lottery Powerball jackpot and appreciate the interest of the public, the State of Florida and the lottery."

She asked for privacy and referred any further inquiries to her lawyer and her financial adviser.

MacKenzie lived in a small blue-gray concrete block duplex surrounded by oak trees, mobile home parks and across from a cow pasture. She was not home on Wednesday but her tan four-door Taurus sat in the yard.

No one knew she had won until news crews started lining up on their small country road on Wednesday afternoon.

Dawn Gourlay, 42, an artist who lives down the road, said she regularly chatted with MacKenzie on the older woman's daily morning walks.

"I talked about cats and she would listen," said Gourlay as many of the neighborhood felines ate from bowls in Gourlay's yard.

MacKenzie was vigilant about crime in the neighborhood.

"She was one of the neighborhood watch people," Gourlay said. "I think she liked the quietude of the neighborhood. But I'm sure she's not going to stay there anymore."

The last time neighbors saw her was about a week ago when she returned to the home with her son after being gone for a week or more.

The winner's name had to be revealed under Florida law, but the recipient had no obligation to publicly acknowledge the prize, lottery officials said.

The winning numbers from the drawing were: 10, 13, 14, 22 and 52, with a Powerball number of 11. The odds of winning were put at 1 in 175 million.

The grand prize in the May 18 drawing had accumulated over two months, and surpassed the previous record Powerball payout of $587.5 million set in November 2012.

The largest jackpot in U.S. history stands at $656 million, won in the Mega Millions lottery in March 2012. That prize was split between winners in Maryland, Kansas and Illinois. (Reporting by Bill Cotterell; Additional reporting by Saundra Amrhein in Zephyrhills, Florida; Writing by Jane Sutton; Editing by Tom Brown, Gunna Dickson and Lisa Shumaker)