Well, today a troy ounce of silver is worth $40.66 (April 13, 2011) so unless that is a rare piece I wouldn't expect it to be worth any more.
8-24-11>>> The current spot price of silver is $41.08 per ounce, that's the value of it. It's not a coin.
It's worth whatever silver is worth at any given point. As of 24 June 2012, silver is worth $26.81/ounce.
The value is only for the silver. Today 1-8-13 silver is at a little more than $30.00 per ounce.
Novelty and holiday silver bars/rounds generally don't have any premium or collector value. As of 23 September 2015, a one ounce piece is worth $14.86.
the current valve of a troy oz of sliver.
What you have is a piece of silver bullion made by a private silver company. Its value is whatever the value of an ounce of silver is. As of October 18, 2007, silver was $13.85 per troy ounce. You can check the current spot price of silver at Kitco.com: http://kitco.com A dealer will usually buy these bullion pieces at about 90% of the melt value, and sell them at about 110% of the melt value, as they have to make a profit in order to stay in business. At $13.85/oz, expect to get about $12.50 for it, and expect a scrupulous dealer to charge no more than $15 for the same piece.
Its value tracks the spot price of silver, currently about $13 an ounce.
The U.S. Silver Eagle is one troy ounce of pure silver. As of 22 January 2013, it's worth $32.
A 2007-W Silver Eagle is one Troy ounce of pure silver.
The silver value of such a bar would be about $2.25 (based on the December 14, 2007 price of silver of $13.98 per troy ounce). An expert would need to see the design and condition of the bar to determine if it had numismatic value above the intrinsic metal value.
The spot price of any commodity can vary from one minute to the next, but during December 2007, silver has been priced around $13.50, give or take a dollar, per ounce.
Since silver certificates have not been produced since the 1960's, I assume that you're asking about a privately issued ingot that is cast in the shape of a dollar bill. I would guess that it is worth its bullion value (silver as of October 9, 2007 is $13.45 per troy ounce).
The spot price of silver fluctuates daily. See the Related Link for "Kitco: Spot price of precious metals" for the current value. According to this morning's paper (April 23, 2007), yesterday's price for one troy ounce (31.1 grams) was $14.33 if you buy a 1000 Tr Oz. ingot. If you buy smaller ingots, the price per ounce is greater.
What is the price of a silver eagle now today
Unless you find someone who is a big JFK collector, this bar is worth the amount of silver from which it is made. As of May 21, 2007, that is around $13.
The approximate value of your coin according to Numismatic News Coin Market Monthly Price Guide for March 2007: 1990 Silver Eagle = $18.00
If you check the back you'll find that you have a halfdollar. There has never been a US-issued Kennedy silver dollar.