$13,000
In September 2009, two employees unpacking a box containing shoes left for donation at a Goodwill store in Marshfield, Wisconsin discovered an envelope containing 130 $100 bills. The shoe donor was unaware of the money inside the box, which had been stored there by her husband.
Source: The Marshfield News (Wisconsin), 9/29/2009

$2.3 million
In May 2009, a New Zealand couple who ran a rural gas station absconded with $2.3 million taken from their bank account after their bank mistakenly raised their credit limit from $61,000 to $6.1 million on May 5, 2009. As of July 2009, Leo Gao and Katherine Hurring were believed to be somewhere in China.
Source: Associated Press, 5/22/2009

$1 million
On March 26, 2006, Shahla Ghannadian left her Louis Vuitton purse with her husband while doing some sightseeing in Sausalito, Cal. The purse contained over $1 million in jewelry, including a Cartier watch, diamond rings, pearl earrings, and several large diamond necklaces which she had worn to her daughter's wedding two days before. After returning to their hotel, the Ghannadians realized the purse was missing. they retraced their steps, but the purse was lost. After the couple flew back to their Toronto home that night, they recieved a call from Sausalito police telling them that the purse and its contents had been found on a park bench by Mr. Suhrhoff, who promptly brought it to the police.
Source: San Francisco Chronicle, 3/29/2006

$5,200
On Dec. 18, 2007, a 71-year-old shopper at Dillard's in a mall in Vero Beach, Florida found $5,200 in stuffed into a Reebok sneaker he was trying on.
Source: Stuart (Fla.) News, 12/20/2007