Gyroscopic Investing

20-30 pounds of silver coins is quite a pile.

I'm not sure what you mean by liberty dollars.  Morgan dollars and peace dollars are the typical silver dollar, walking liberty half dollars resemble the American Silver Eagle (or I guess it is the other way around). 

Do you know how/when the coins were accumulated?  If around the time silver went out of circulation (1965) they may be just 90% "junk" silver pulled from circulation.  Which, at $20+ per ounce of silver is not so junky.  The ones in individual holders do suggest the potential for numismatic value.  And if you do have Morgan or peace dollars, those are 90% silver but they typically command a premium over the value of the metal.  Sometimes a significant premium.

You can pick up The Guidebook of US Coins (the Red Book) and see if you do have coins with numismatic value.  You can also peruse the Bay for a pretty good idea of current market value for those coins.

To sell you could, of course, take the whole lot to a coin dealer and see what they offer.  But I suggest you consider doing a bit of study to get a rough idea of what you actually have.  Selling on EBay is likely to yield a higher price, but that takes some knowledge of what you are selling and is somewhat time consuming.

Good luck!

Blue book is supposed to be "bid" prices.  No one believes them.  Red book contains "ask" prices.  Again, no one believes them, but they do provide relative values.  Either one is probably fine, if you use them as a guide to relative value.  EBay is probably the best real-time "price guide".

I second the reccommendation for picking up a redbook, if only so you don't end up selling an 1893-s morgan or something similar for melt :p.

Concur on the red book, also check out http://www.coinflation.com/unitedstates/

Shameless plug for Rare Coins of New Hampshire.
It's who the coin enthusiasts in my family use. Very honest.