Tracey Berry owner of the Cool Country Tavern in Trentham found the 148-gram nugget while cleaning a fireplace grate. The nugget most likely fell from the brickwork of the building, which is located in a 19th century gold mining region.
Ian Semmens, a gold mining expert, told the Herald Sun newspaper that "up until the 1890s it was common for people to hide gold inside their homes."
The nugget is believed to be worth about $5,000 (US $4,557), the Australian Broadcasting Corp. reported.
At first Berry said many people doubted the nugget was real.
"We didn't really believe it," she said.