If you are looking to invest in silver, you have several options. There are certainly silver stocks, but these will not necessarily mimic the price of silver. You can buy the silver ETF (symbol: SLV). Another option is, of course, to buy the actual metal.
If you are going to buy actual silver, you should buy coins. For one ounce coins, the U.S. silver eagle is the most recognizable. You will pay a slight premium above the price of silver. If silver is going for $40 an ounce, you may pay $43 or $44 for an eagle.
An even better way to buy silver coins is to buy dimes, quarters, and half dollars that were minted before 1965. These coins are made up of 90% silver. If you want to figure out the weight of silver for these coins, take the face value and multiply it by .715. The actual content of silver was a little higher when they were minted, but due to wear and tear, the .715 figure is generally accepted. Because the half dollars were not circulated as much and because they are not quite as common, they may demand a slight premium.
For an example, let's say that you have 4 quarters dated 1964 or earlier. The face value is one dollar. Multiply one by .715. This is how many ounces you have. If the going price of silver is $10 per ounce (I know, that seems ridiculously low now), then the 4 quarters would be worth $7.15. If the price of silver is $40 per ounce, then the 4 quarters would be worth $28.60 (.715 x 40).
The same calculation would hold for 10 dimes (one dollar face value). If you have 10 dimes dated 1964 or earlier and the price of silver is at $40 per ounce, then they would be worth $28.60. The same would be true of two half dollar coins, although it might be slightly more due to the premium.
Collecting these coins is easy and convenient. If you don't have a lot of money to invest in silver and you want to accumulate slowly, this is an easy way to do so. It is also a good investment because you don't have to pay much of a premium right now. There may be more of a premium in the future, but then you would benefit if you own some already. If any coin dealer is trying to sell these coins for a high premium, then you should go elsewhere. They are not marked up to the same degree that a one ounce eagle would be.
These coins could actually be used as money in a breakdown of the system (which we should all hope will never happen). They are in a small denomination and are easily recognizable.
I don't see much of a downside to owning a few of these coins except the possibility of the price of silver going down in the short run.