All of the above info is good advice and yes you will need a reference book which will tell you if you have a scarce date in the mix. My aunt asked me to sell her coin collection a couple of years ago and I sold stuff on ebay, some to friends and most to a coin dealer I trusted. The hardest part in selling unslabbed coins is grading. Gold coins do well on ebay. I went to the local book store and purchased at that time 2003 North American Coins and Prices book as I had a lot of Canandian. It lists your Texas Centenial 1/2 dollar from $90 to $160 2 years ago. Good luck and enjoy.