These are beautiful silver coins and are they are worth their weight in silver. Computing an accurate value for them takes a little work. First, go to kitco.com and find the current price of silver. Let's say by way of example it is $20 US dollars per troy ounce. Be sure to look it up. It changes every day.
Continuing our example, your coin contains $20 worth of silver, so $20 is its Base Value (BV). The BV is very close to the value of your coin. Only when your coin is in superb numismatic (coin collector) condition is it worth more than BV. Sometimes these coins appear in numismatic slabs. A sample slab appears in our second picture to the right. Coins slabbed by PCGS, NGC, ICG, and ANACS (not other brands) are worth more than BV:
circulated coins: BV
fully uncirculated coins: BV + $3
coins in numismatic slabs graded MS69: BV + $10
coins in numismatic slabs graded MS70: BV + $20
In almost all cases, specific dates of these coins do not matter. In one exception, the 1996 silver eagle has a lower mintage than all the other dates, so it carries more value (about twice) than non-1996 issues.
Recently the US Mint has been marketing special issue coins labelled 'burnished' and 'enhanced.' Some collectors like these variations and and willing to pay a little more, maybe $10 or $20, for them.
If you have a proof US Silver Eagle, they carry different values than regular coins. See this CoinQuest page for an analysis of proof Silver Eagles.