Variety Equivalents: 
Crosby 9-I, Breen 1642

Notes:
This variety was discovered in 1897 by Edouard Frossard.  In 1958, Sheldon knew of four examples of this variety, two of which turned up following the 1949 publication of his book, "Early American Cents."  The fifth example was discovered by Chris Young.  Sheldon referred to this variety as a "freak mule" because it was an extremely rare combination of two dies that were otherwise common when they were used on other varieties.  Allegedly, Dorothy Paschal offered Dr. Ruby a house in Brooklyn in trade for his example of this variety.  He turned her down, but she subsequently located a slightly nicer example on her own! 

The obverse die for this variety was also used on:
1793 Sheldon 8 
1793 Sheldon 9

The reverse die for this variety was also used on:
1793 Sheldon 10

Images courtesy of Jim Neiswinter

Known examples (6):
1. Davidson - 1955 ANA Convention sale - Dorothy Paschal - Dr. William H. Sheldon - Naftzger - Eric Streiner - donated to Yale University in 1993.  Sheldon called this one VG-8; Del Bland netted it out at VG-8 (sharpness of VF-20 but corroded).  This example is generally believed to be finest known of the variety.

2. Dr. Charles Ruby (who discovered this coin in 1950) - Gus Portman - Robinson S. Brown, Jr.  Sheldon called this one a Fine-12 ("finest reported); Del Bland netted this one out at VG-7 (sharpness of VF-20 but surfaces very rough).

3. Gilbert - Brand - Charles Williams - Starr - Jack H. Robinson - Dan Holmes.  Sheldon called this an AG-3, Del Bland called it Good-5.

4. "G-5, sharpness of VG-10" (illustrated above). Ex - Chris Young - Dr. Roy Sturgeon - Bowers and Merena Galleries "The Rarities Sale, Orlando", January 8, 2002, Lot 26, illustrated, sold for $10,350.00 - Jim Neiswinter

5. Frank L. Bowman - Ed. Frossard - Hall - Brand - Clapp - American Numismatic Society.  This was the first example discovered of the variety.  Del Bland graded this one Good-4.

Sources and/or recommended reading:
"Penny Whimsy" by Dr. William H. Sheldon

"United States Large Cents 1793-1814" by William Noyes

"Walter Breen's Complete Encyclopedia Of U.S. And Colonial Coins" by Walter Breen

"Walter Breen's Encyclopedia of Early United States Cents 1793-1814" by Walter Breen

Relevant collector organizations:
Early American Coppers Club