Hey There, Wood v. Boynton Fans!

As CNN reports here, a man, who seems to have chosen anonymity, bought a small floral bowl at a garage sale for $35.  It turns out to be a 15th-century antique commissioned by the Ming dynasty’s imperial court and worth around $300-500,000.  The buyer must have suspected that the bowl was valuable, as he sent photographs to specialists shortly after the purchase.

Unilateral or mutual mistake?

Between buyer and seller, who ought to bear the risk of this mistake?