What is the value of a 1965 US cent?

If you found it in change, one cent. 1.5 billion cents were struck that year so they are definitely not rare. A nice uncirculated one might retail for 25 to 50 cents.

US Coins dated 1965 through 1967 don't have mint marks even though they were struck at all three then-active mints. The Mint suspended their use until enough coins could be made during the switch from silver to clad composition.