The reasons of a coin having an image only on one side are varied. I suggest you take the coin to a coin shop and have it appraised to get a more accurate estimate of value.
This sounds like someone either was creating a novelty giveaway or had just gotten a number punch set and was fooling around with it. Unfortunately, in either case this is considered to be a damaged coin and has no numismatic worth above its face value.
The value of a quarter with one side stamped heads and the other side blank would be 25 cents in terms of its monetary value in the United States. The design on the coin does not affect its face value or purchasing power. This type of coin may have been altered or misprinted, but as long as it is recognized as legal tender, it can be used for transactions at its full 25-cent value.
5 cents. It was mass produced for the Lewis and Clark commemorative in the fall of 2006. The nickel had different designs over the 2004-2006 mintings.
This type of error of misstruck coins is called 'Brockage'. A Lincoln penny with this error is valued at $35.00
I'm not sure what you mean "mixed with a penny". If the coin is made out of copper-nickel like an ordinary dime, but has a cent image struck* on top of the dime image, that's possibly a mint error that happened when a dime accidentally got mixed in with cent blanks and was struck a second time. That's definitely a collectable error but you'd have to take it for in-person appraisal to be sure. If one side is a cent and the other side is a dime, it's a fake made by joining halves of 2 genuine coins, and has no value other than as a curiosity. (*) FWIW, coins are said to be struck or minted, rather than "stamped".
A 1984 nickel with one side stamped with Jefferson and the other side blank is likely a novelty coin created after minting. It does not hold any numismatic value to collectors and is worth face value, which is 5 cents.
It's a 1902 Liberty Head Nickel with a value of $3.00-$5.00 in average condition
It is a mule.
That is what is known as a war nickel, because nickel was needed for WWII, it was needed to change the composition of the nickel to one including 35% silver, as of the time of writing, your coin is worth $1.64 in silver content alone.
This sounds like someone either was creating a novelty giveaway or had just gotten a number punch set and was fooling around with it. Unfortunately, in either case this is considered to be a damaged coin and has no numismatic worth above its face value.
The US Mint did not issue an 1896 nickel with an "S" stamped on it. If you have one then it would seem as though someone stamped the coin sometime after it left the mint. Also please don't assume that because a coin is old it has to be made of silver. All US nickels except special "war nickels" made during 1942-45 are struck in the same alloy of 25% nickel and 75% copper.
The value of a quarter with one side stamped heads and the other side blank would be 25 cents in terms of its monetary value in the United States. The design on the coin does not affect its face value or purchasing power. This type of coin may have been altered or misprinted, but as long as it is recognized as legal tender, it can be used for transactions at its full 25-cent value.
5 cents. It was mass produced for the Lewis and Clark commemorative in the fall of 2006. The nickel had different designs over the 2004-2006 mintings.
It was made in either Belgium or one of its colonies.
I have one and it is a 7x57 caliber is stamped on the left side of the barrel.
This type of error of misstruck coins is called 'Brockage'. A Lincoln penny with this error is valued at $35.00
A half dollar and a nickel. One of them isn't a nickel, the other one is.