The value of an 1811 Cornish penny depends on several factors such as its rarity and condition. These pennies were used in the mining communities of Cornwall and Devon in England. They are not a legal form of currency and mostly made for ceremonial and decorative purposes. Generally, an 1811 Cornish penny can have a value anywhere between a few dollars to several hundred dollars, depending on its grade and rarity. Numismatic value can be determined by evaluating factors like wear, luster, and overall appearance. It is recommended to consult with reputable coin dealers or experts in numismatics to get an accurate appraisal of its worth.