Penny values are determined using a step by step method. How much your old penny is worth ranges from 2 cents for wheat pennies to thousands for early and rare colonial era cents. Steps identify, series, dates, and mintmarks. Condition is graded comparing to images, video, and descriptions.
I found a $372,000 penny in a roll of coins - you know if you struck gold when you use the 'magnet' trick
Pennies that can be worth up to $7,500: How to know if I have one - AS USA
Lincoln Penny (1909-1958) Value
You could have a penny worth $7K in your pocket — and not even know it
10 Most Valuable Pennies: Are These In Your Pocket Change?
Wheat Pennies (1909 to 1958) Values
How to Find The Value Of Old Coins: 3 Ways to Find Prices
Wheat Pennies Showing Progression of Grades, Uncirculated
1943 Steel Penny Value: How Much Steel Penny Coins Are Worth Now?, by Bullion Shark LLC