ResearchCoin Shooter's Guide to US Circulated Dollar Coins
When prospecting with a metal detector, United States dollar coins are a good find. Common enough that you will find a few, but rare enough to be worth the time. The thing to remember about collectible coins is that condition is everything. There are 70 grades in the American Numismatics Association grading system, with grades 60 through 70 designating mint state, uncirculated coins themselves! The coins you find on the ground aren't likely to score better on this system than 40 on this scale, and ten grades of condition can make hundreds of dollars of difference in collector's value, so don't get your hopes up too high. Note that there are also non-circulated US coins as well, such as Gold Eagles and commemorative editions, which don't fit in this category. Going back in time:
Sacagawea dollars - goldish to brown finish, obverse female native American, reverse flying eagle. Most misguided coin ever minted. Composed of a copper-manganese alloy that must have looked good on paper - unfortunately the finish doesn't last longer than it takes the mint truck to drive to the bank! Copper and manganese is an extremely unstable mixture, and the coin is likely to degrade into green and brown spots. Even mint state coins degrade, making this a disappointing series for collectors. Worth a dollar, if you can even get somebody to acknowledge it as a spendable US coin.
Susan B Anthonies - nickel finish, composed of copper clad in nickel. Obverse woman with hair in bun facing right, reverse eagle landing on the moon. Common as dirt. Even mint state specimens sell for little over face value. Still widely circulated; you can get a handful in good condition at banks and post offices. If you find it in a field, spend it.
Ike dollars - large circumference, usually copper-nickel but some silver varieties exist. Obverse Dwight D. Eisenhower's famous bald head looking left, reverse US Liberty Bell and the moon. Sometimes a good find, these are still in circulation in some places, and some varieties may fetch double face value even with wear. Kind of "iffy" though, most likely spendable.
Anything after in this list is no longer in circulation by any stretch of the imagination - but you may get lucky enough to find:
Peace dollars - What a chunk of silver! Net weight of over 0.77 ounces pure silver with some copper, heavy in your hand. Obverse Lady Liberty with spiked crown facing left, reverse standing eagle perched on a rock with the word 'peace' visible. An excellent find for the melt value alone, and the later end of the series from 1927 onward may be worth tens and even hundreds of dollars to a collector even in poor condition. Anything 1922/1923, however, was so over-minted that it's worth more in silver value than collector's value, even in mint condition.
The Morgan dollars - What a chunk of silver! Same composition as Peace dollar, with the identical concentration of 0.77 ounces silver with some copper and noted to discolor slightly although this enhances their value to some specialists; obverse very old-style Lady Liberty, reverse classic eagle with wings spread clutching arrows and decked by a laurel wreath. The most avidly-collected dollar coin series - due to the long mintage from 1878 to 1921 some numismatists specialize in just this coin. Depending on year alone, even a well-worn specimen of this series may be worth anywhere from tens to tens of thousands of dollars. Go straight to a coin dealer to have it appraised before you even think about melt value. Guaranteed to make your day.
Anything in dollar coins before this was minted prior to 1877 and is more likely to be part of a treasure horde or time capsule than to be found loose.