The following is excerpted from Clifford Mishler’s Coins: Questions & Answers
Q: My father gave me a 1966-D Lincoln cent he received in change on which “Liberty” is misspelled “LIBIERTY.” Is this an engraver’s error? Is it valuable?
A: Your cent is an example of the popular striking oddity known as the “BIE” error. It was caused when a portion of the die between “B” and “E” broke away, leaving a sharply delineated depression in the die, which raised what appears to be an additional “I” in LIBERTY. The BIE error is quite common in its cruder expression; that is, with the extra “I” being generally featureless and of less than full height. They are of little value. However, examples where the I is attractively formed, such as the 1959-D BIE cent, have commanded substantial premiums. Such defective die varieties of cents, nickels, dimes, and quarters typically command valuations in the $10 to $25 range.
Robert J. Obermeyer says
During 1965, 1966 and 1967, both the Philadelphia and Denver mints were in production for cents, nickels, dimes, quarters and half dollars. During these years the Philadelphia and Denver mints did not use a mint mark on all the coins it produced for circulation. If someone received a 1966-D cent, then consider it a counterfeit/fake item. You can not tell the difference as to which mint the coins came from. (The Philadelphia mint did not use mint marks for circulation coins until 1980 and then started to use a P mint mark.)