My mother passed away and I found three stock certificates for some Sears, Dean Witter Discover, and Morgan Stanley and I was wondering how I could find out what they are worth and how to cash them in. The Sears stock certificate was purchased on May 9, 1988 for 8 shares and the Dean Witter is for three shares purchased January 14, 1997 and Morgan Stanley is for six shares purchased on January 26, 2000. Any help would be appreciated.

Since this is not homework, I've moved it some place more appropriate.