Long considered the key date in the set, the 1856 Flying Eagle holds legendary status among coin collectors for its overall popularity. Business strikes of this issue are somewhat controversial, as some experts consder all 1856 Flying Eagle cents to be struck in proof format, even if the mirror finish isn't pronounced. Rick Snow, noted author and researcher of the series, has stated in his reference book that only two die varieties (S-3 & S-9) are to be considered as business strikes.
| Country | United States of America |
| Year | 1856 |
| Serie | Flying Eagle Cents |
| Denomination | 1c |
| Mint | Philadelphia |
| coinage-type | Flying Eagle |
| desg | MS |
| designer | James B. Longacre |
| diameter | 19 |
| edge | Plain |
| material | 0.880 Copper; 0.120 Nickel |
| mintage | 2,000 |
| ngc-id | CSK7 |
| obverse-description | An eagle with wings extended in full flight fills the central obverse design with the words UNITED STATES OF AMERICA around the top periphery. The date is centered at the bottom. |
| pcgs-link | 2013 |
| pcgs-number | 2013 |
| prefix | Key Date |
| reverse-description | The reverse bears the denomination of ONE CENT in the center surrounded by a wreath bearing a ribbon tied in at the bottom center. |
| variety | Flying Eagle |
| weight-grams | 4.67 |
| year-display | 1856-1858 |