Yes, they are worth face value (one cent each). Please check your pocket change - only cents from Denver and San Francisco carry mint marks. Cents struck at Philadelphia and West Point do not have mint marks so they are indistinguishable from one another.
Generally, common date pennies without mintmarks are not particularly valuable unless they are in exceptional condition or part of a rare error. For these specific years, unless they are in uncirculated or proof condition, their value would likely be based on their metal content which is mostly copper. It's recommended to have a coin dealer or appraiser assess them for a more accurate evaluation.
A 1941 penny without a mintmark means it was minted in Philidelphia.
A Lincoln cent without a mintmark was struck at the Philadelphia Mint. The Mint does not use "P" mintmarks on penny's.
Low grade coins retail at 25 cents to $1.25, better grade can be $3.00-$5.00
If it is a proof then it will have the mintmark "S". If your coin doesn't have the mintmark "S" then it is just a normal coin.
There is no mintmark on the 1921 British Penny, they were all minted at the Royal Mint London.
SIMPLE ANSWER: No US coin dated 1965, 1966 or 1967 will have a mintmark, it's just a penny.
If there is a mintmark at all, it will be a very small "H" to the left of the date in the exergue. The "H" indicates it was minted at Heaton in Birmingham. All 1912 Pennies without a mintmark were minted at the Royal Mint.
A mintmark is a small identification mark used to tell which mint it was made in.
underneath the year
It will have a S mintmark.
An Australian Penny or Halfpenny with a "Y." (PENNY.) mintmark indicates that the coin was minted at the Perth Mint. An Australian Penny or Halfpenny with a "I" mintmark indicates that the coin was minted at either the Calcutta or Bombay Mints in India.
Philadelphia. Cents (pennies) from the Philadelphia mint have never carried a mintmark.