In 2007, a New Yorker paid $3 for a white bowl at a yard sale and kept it in the living room for years; experts later identified it as a 1,000-year-old Chinese artefact, and it sold for $2.225 million

• Pic credit: Sotheby'sEvery New Yorker has walked past a yard sale and kept walking.
• The folding tables are full of chipped mugs, mismatched lamps and vases nobody has ever wanted.