The Maine penny, also referred to as the Goddard coin, is a Norwegian silver coin dating to the reign of Olaf Kyrre King of Norway (1067–1093 AD). It has been suggested as evidence of Pre-Columbian trans-oceanic contact.  
Guy Mellgren, a local resident and amateur archaeologist, said he found this coin on August 18, 1957 at the Goddard Site. This was an extensive archeological site at an old Native American settlement at Naskeag Point on Penobscot Bay in Brooklin, Maine. A 1978 article in Time Magazine called the discovery site an ancient Indian rubbish heap near the coastal town of Blue Hill. Over a lengthy period, a collection of 30,000 items from the site were donated to the Maine State Museum. The coin was donated in 1974.
Much of the circumstances of the finding of the coin were not well preserved in the record (as was the case with the majority of the 30,000 finds). The coin was at first mis-identified as a British penny from the 12th century. In 1978, experts from London considered that it might be of Norse origin. Today the identity of the Maine Penny as an Olaf Kyrre silver coin is not in doubt. Kolbjorn Skaare of the University of Oslo determined the coin had been minted between 1065 and 1080 AD and widely circulated in the twelfth and thirteenth centuries. By some accounts the penny was found with a perforation, hinting it was used as a pendant. This area of the coin is said to have since crumbled to dust from corrosion.
The Goddard site has been dated to 1180–1235, within the circulation period of pennies of this type. The people living there at the time are generally considered to be ancestors of the Penobscot. While the date is around two hundred years after the last of the Vinland voyages described by Norse sagas, it is well within the period during which the Norse lived in Greenland and could have possibly visited North America.
The penny's coastal origin has been offered as evidence either that the Norsemen from Greenland traveled further south than Newfoundland or that the coin might have been traded locally. However, the penny was the only Norse artifact found at the site, which according to substantial evidence was a hub in a large native trade network. For example, a single artifact generally identified as a Dorset Eskimo burin was also recovered there, and may support the idea that both the burin and the penny could plausibly have come to Maine through native trade channels from Norse sources in Labrador or Newfoundland.
It has been suggested that the explanation that the coin was either brought by Vikings or traded from a Viking Era site is weak because no coinage has been recovered from the Viking Era archaeological site of L'Anse aux Meadows on the northernmost tip of the island of Newfoundland. Furthermore, the Newfoundland site dates from around two centuries earlier than the Goddard site and was subject to an orderly evacuation.
The Maine State Museum website favors the view that it was found at the site and is therefore evidence of Norse presence on the North American continent, although the Museum states "the most likely explanation for the coin’s presence is that it was obtained by natives somewhere else, perhaps in Newfoundland where the only known New World Norse settlement has been found at L’Anse aux Meadows, and that it eventually reached the Goddard site through native trade channels." The Maine State Museum describes it as "the only pre-Columbian Norse artifact generally regarded as genuine found within the United States".
However, the possibility that it may be a hoax has been raised. Notably this Norwegian silver coin and other similar coins of that era were available on the open market during 1957. Thus, Mellgren could have the means and the opportunity to plant the coin at the site, or he could have been deceived by someone planting the coin – though it is unclear what the motive may have been. An assessment of the validity of the find by anthropologist Edmund Snow Carpenter concluded: "Not proven".
The American Numismatic Society has stated that "There is no reliable confirmation on the documentation of the Goddard coin, and much circumstantial evidence suggests that someone was deliberately trying to manipulate or obfuscate the situation. The Norse coin from Maine should probably be considered a hoax."
- Beardmore Relics - Edmund Snow Carpenter likened the Norse coin from Maine to the Beardmore Relics, which were said to have been discovered in Ontario in the 1930s.
- "The Viking ”Maine Penny” Mystery". Thor News. February 21, 2014. Retrieved October 15, 2015.
- "Mysterious "Maine Penny" Discovered". The History Channel. February 21, 2014. Retrieved October 15, 2015.
- Carpenter, Edmund (2003). "Norse Penny" (PDF).
- "Science: Bye, Columbus". Time Magazine (Vol. 112 No. 24). December 11, 1978.
- "The Controversial Origins of the Maine Penny, A Norse Coin found in a Native American Settlement". Ancient Origins. March 1, 2015. Retrieved October 15, 2015.
- Sutherland, Patricia. (2000) The Norse and Native Norse Americans in William W. Fitzhugh and Elisabeth I. Ward, eds., Vikings: The North Atlantic Saga (p. 238-247. Washington, DC: The Smithsonian Institution)
- The Norsemen in Greenland: Recent Discoveries at Herjolfsnes by William Hovgaard (Geographical Review. Vol. 15, No. 4, Oct., 1925, pp. 605-616)
- "Archeological Evidence of Native Contacts in Vinland". Smithsonian Institution. Retrieved October 15, 2015.
- "The Goddard Norse Coin". Maine State Museum.
- "Current Cabinet Activities". American Numismatic Society. Spring 2005.
- Prins, Harald E.L., and McBride, Bunny, Asticou's Island Domain: Wabanaki Peoples at Mount Desert Island, Maine, 1500-2000 (Vol.1., pp.40-42. Boston: National Park Service, 2007)
- Skaare, Kolbjorn (1976) Coins and Coinage in Viking-age Norway (Oslo: Universitetsforlaget) ISBN 9788200015420
- Bourque, Bruce (2004) Twelve Thousand Years: American Indians in Maine (University of Nebraska Press) ISBN 9780803262317
- Haviland, William (2012) Canoe Indians of Down East Maine (The History Press) ISBN 9781609496654
- Hovgaard, William (1914) The Voyages of the Norsemen to America (New York: The American-Scandinavian Foundation)
- Richard, Wilfred E.; William Fitzhugh (2014) Maine to Greenland: Exploring the Maritime Far Northeast (Smithsonian Institution) ISBN 9781588343796