George Washington's Wallet and Hair

In 1799 George Washington's old, worn out wallet was stolen from its case in The Old Barracks Museum in Trenton. New Jersey. It was returned. In a much stranger incident in 1986, a lock of Washington's hair was stolen from a French museum and five years later it was found together with a lock of hair belonging to the Marquis de Lafayette during a police raid on a drug's den.
Bull Semen

$10,000 worth of frozen bull semen and embryos was stolen from the dairy building at California Polytechnic University. The embryos were found but the semen was never recovered although a $1500 rewards was offered.
Twenty Foot Chicken

El Pollo Loco fast food chain, in Sherman Oak, California, celebrated its new franchise by erecting a twenty foot inflatable chicken in front of the restaurant. Two weeks later someone stole it. A reward of 12 free chicken combos was offered for its safe return but it was never found. The question here is, where can you hide a twenty foot inflatable rubber chicken?
Mary's Little Lamb

A statue of Mary's little lamb was erected in Sterling, Massachusetts, to commemorate Mary Sawyer who was the inspiration for the nursery rhyme written in 1830 by Sarah J. Hale. On June 30th 1990, the lamb was stolen. It was returned some weeks later.
Buttons

The wife of Panamanian dictator, Manuel Noriega, was arrested in a shopping mall in Florida in March 1992. Felicidad pleaded guilty to stealing $485 worth of buttons. They had cut them all from garments in the clothing department.