What is the value of a 1918 silver dollar?

You need to supply much more information - mint mark, condition, and most importantly why you think it's mis-struck. If you're referring to the spelling of the Word TRUST in the motto In God We Trust, that is not a mistake. There are several other threads on this site explaining the use of the Roman alphabet on coins of the 1920s. It only had 24 letters, and what we write as U and J were replaced by V and I respectively.