Kara's bracelet
From Smallville Wiki
When Kara lost her memory and her powers, the bracelet was her only link to her Kryptonian past. When she was in Detroit, Kara dropped her bracelet while being chased by Finley; Lex Luthor found it but soon after was shot by Finley. The bracelet turned up later in Lionel Luthor's vault; presumably, Lionel found the bracelet when his son was medivaced from Detroit to Smallville.
Lex Luthor blackmailed a meteor-enhanced Pete Ross into stealing the bracelet from Lionel. Clark Kent stopped Pete from giving it to Lex, but Pete overpowered him with kryptonite and went to see Lex anyway. Pete left the bracelet behind.
Lex had his henchman torture Pete for information about the bracelet, but Pete refused to give it up. Clark saved Pete, and knocked out Lex and his henchman. Because Kara had lost her memory, Clark was afraid to give her back her bracelet; he worried that it might trigger memories about her past that Lex could then find out. He hid the bracelet under the floorboards of his barn.
After Jor-El restored her powers, Clark gave Kara back her bracelet.
