Go to your local library and find a copy of a book called Photograde. It's probably the best resource available. Failing that, you can look for the famous Red Book from Whitman Publishing. It's mostly a value guide, but has some fairly decent information about grading as well.
The 1923 Mercury dime is a common date coin, average circulated coins are $4.00-$7.00, better grade are $15.00-$30.00.
You have a Barber dime; Mercury dimes started in 1916. The value depends on its grade & mint mark, but it's worth at least $4.00 just for the silver.
A 1942 Mercury silver dime could be worth between $2.00 and $30.00 depending on its condition and grade.
If it's a U.S. dime with a date of 1944, it's a Mercury dime.
The first MERCURY dime was struck in 1916
The Mercury Dime
The Winged Liberty Head Dime also known as the Mercury Dime was minted from 1916-1946.
The U.S. Mint did not issue a Mercury Dime in 1910.
The Winged Liberty, or Mercury Dime. Most people call it the Mercury Dime, but its real name is the Winged Liberty dime.
It worth about $2.00 just for the silver. All Mercury Head dimes are 90% silver. The collectible value of any coin depends on date, mintmark and grade.
Do a Google image search for "Mercury Dime" and you will see the photo of the dime.
1936 is a very common date Mercury Head dime. Most coins of this type have seen heavy use and show a lot of wear. In general retail values for low grade coins are $3.00, better grade are $4.00. The "W" you see is on all the dimes of this series, it's the designers monogram.