Significant examples:
"VG-10".  Ex - Stack's sale of the "William Van Roden" collection, May 1968, Lot 200 - E. Exman in November 1972 - Kagin's sale of the "Philip Van Cleve" collection, February 1986, Lot 5101 - Superior Stamp & Coin's sale of the "Jack H. Robinson" collection, January 1989, Lot 174 - Superior Stamp & Coin's sale of the "Robinson R. Brown" collection, January 1996, Lot 134 -  John Whitney - Stack's "65th Anniversary Sale", October 17-19, 2000, Lot 64, "(EAC: Good-4)", illustrated, sold for $6,037.50

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

"Walter Breen's Complete Encyclopedia of U.S. and Colonial Coins" by Walter Breen

Relevant collector organizations:
Early American Coppers Club