A dark, rundown home passed by hundreds of motorists each day played host to an "elaborate" novel magic mushroom laboratory, police allege.
More than 46 kilograms of the mushrooms - grown in 60-litre storage containers and worth nearly $700,000 - were seized from the property at Merrylands Road, Greystanes on February 3.
"It's quite uncommon," Acting Superintendent Simon Glasser told reporters on Tuesday.
"On record, this is one of the largest ones ever in NSW."
One man is before the courts over the alleged fungi felony.
Michael Serretta, 26, didn't apply for bail when his case was mentioned in Parramatta Local Court on Tuesday.
He was already in Parklea prison after police allegedly found him driving in West Pennant Hills on February 3 with magic mushrooms, cocaine, two knives and more than $50,000 in cash.
He's now also facing charges of large commercial drug manufacture, large commercial drug supply and conducting a drug premises.
"It was quite an elaborate set-up, it was a professional operation and we believe there were more involved than the man we've arrested," Supt Glasser said.
Serretta will return to court in April.