Police said the man, who lives at Gilbert Camp in the hills above the capital Honiara, had dug down several metres on Saturday, when he struck something metal.
When he discovered it was a WWII shell, he called police and an explosive ordnance disposal team then removed 101 highly explosive shells from the site.
They were 105mm shells of the kind widely used with light field howitzer artillery by US troops in the Pacific theatre.
Last week, a 105mm WWII shell detonated under a cooking fire in Honiara, fatally wounding two men and injuring another two other people.
That tragedy sparked calls for the Solomon Islands government to put more effort into locating and disposing of dangerous World War II bombs and shells, which still present a danger.
The Solomon Islands was the scene of fierce fighting between Japan and the United States in WWII, and critics say the government must put more pressure on those countries to play a bigger role in disposing of the dangerous ordnance left behind.
The officer in charge, Inspector Clifford Tunuki said the police team took two days to remove the shells, on Saturday and Sunday, and also scanned the surrounding area for more unexploded ordnance (UXO).
"Since the UXOs pose great risk, I ask our good people, especially those in Honiara and other province with high deposits of UXOs to report it to police or to have their properties cleared by a UXO clearance company if they intend to develop it," Tunuki said.
Photo RSIPF Caption: The explosive ordnance disposal team remove WW 2 explosive shells from a pit latrine in Honiara