Welcome to Numista. I do not entirely agree with the other members assessment of your Morgan Dollar and stating that it is worth only melt value. While much of what was stated is true, there are mitigating factors when it comes to assessing value and collectability of coins depending on what they are exactly. Yes, the graffitti does diminish it's value and is a major distraction. In addition, your example was cleaned at one time in its life although not harshly. The mitigating factors in this case is that for one it is a Morgan Dollar that is very popular with even the casual collector and the public. Another factor is that yours is from the Carson City mint which across the board are coveted regardless of imperfections such as undesireable graffiti and being cleaned. In the end it is worth what somebody is willing to pay for it. A cleaned 1878 CC Morgan dollar with graffiti on it is better than not having one at all to some collectors. I think you could easily get $40 or more for it if you found the right person who wanted an example.
As for “grade”? Fine Details / Graffiti / Cleaned