Found 4 Pennies at the Post Office

Today I went to the post office to mail a book and on the counter that's along the side to prepare your mail if you didn't do that at home, I found these 4 pennies. 

Then in the parking lot I found a set of keys and this guitar pick. I took the keys inside but kept the guitar pick. What should I do with it?

Have you found any money lately?

This Found Money Facts:
Denomination: 4 pennies
Year:  1996, 1997, 2001, 2006

U.S. Mint: D, D, D, D
Condition:  mostly dirty and tarnished
Total Found Money to Date for 2012:  $8.75