Very definitely, but it depends on their series date and letter, denomination, and condition.
For example the most common silver certificates ($1 1957, 57-A and 57-B) are only worth a small amount above face value because so many were saved, while an uncirculated specimen of the $10 silver certificates printed for use by the military in WWII can sell for over $10,000.
The best way to know is to check the bill's series date and what letter if any is next to the date, then look at a price guide such as the one linked below.
How much is a 1957a silver certificate worth?
The most valuable silver certificate has to be the 1880 $100 note. Even a well-worn example is worth over $4,000 -- and a nice crisp uncirculated one could easily be worth over $100,000
No. If your bill says "silver certificate" it should have black and green ink in the design, while the seal and serial numbers are blue. "Silver certificate" simply means that at the time, the bill could be exchanged for $10 worth of silver. In 1968 that practice was suspended so your bill can't be exchanged today. However it may be worth more than $10 to a collector. Please see the Related Question for more information.
a mint condition silver certificate is worth $5-$6.
An 1899 silver certificate is worth around $40 if in good condition. It can as high as $250 if perfect condition.
Check that bill again. There was no $1 silver certificate dated 1931.
It is worth in circulated $2 at minimum but can reach $14.00It depends on the grade and year. It could be $1 to $1000
It is worth whatever the spot price for silver is on the market and may also be worth more to a collector based on the conditions and markings of the bar.
For the most part, they're worth maybe $1.50 to a collector. A coin dealer won't pay a premium unless it's in exceptional condition, or perhaps a star note.
The U.S. hasn't printed silver certificates since the 1960s, and there was never a $2 silver certificate.
You shouldn't "cash in" a collectible bill. To cash in a bill means to take it to a bank where you'll only get face value (i.e. $1) for it. As you can see from the Related Question linked below, a 1923 $1 silver certificate would be worth much more to a collector or at auction.
This is not a rare date for silver certificates. As of 9-5-2011 it is worth $1.25 to $1.50 in circulated condition. In uncirculated condition it is worth $3 or more. This silver certificate should have a blue seal.