It depends on the condition. One site values a 1923 one dollar silver certificate in very good condition (fairly well-soiled; might be significantly worn; could have roughness around the edges with only minute problems) at $37.00.
It is possible that the condition described above does not reflect your certificate; it might be in better shape. If this is the case, visit: http://www.paradisecoin.com/currency.html and scroll down to find the best description of your bill. This should give you a rough idea. For proper valuation, you can take it to a currency dealer.
A mint condition 1923 silver certificate is currently for sale by Morgan Mint for $99.95.http://www.morganmint.com/product.cfm?Prod=2894&link=32&source=shopping&source=shopping