The value of a 1956 D wheat penny can be found by consulting a price guide, such as those provided by CoinTrackers and USA Coin Book. According to CoinTrackers, as of 2014 a 1956 D wheat penny may be worth between 15 cents and 60 cents.
The actual collector's value of a coin is based on both the rarity of the coin and its current condition. Coins in mint condition fetch the highest value, while those of lower grades may be worth no more than their face value. The Denver mint produced about 1.098 million wheat pennies in 1956. Some 1956 D wheat pennies contain a mint mark error and may be worth up to $100, as of 2014.