How Much are These Worth?

Yesterday when I went to lunch, I received these two quarters as part of my change. (They both are painted on the "tails" side)I have never seen quarters like this. Doing a little research, I have discovered that these quarters represent the American Civil War 150 years ago, and Vicksburg, that is stamped on the coins was a famous battle in Mississippi.

That's nice and all but I want to know, what are they worth?

I'm guessing their worth is only face value, but maybe it's more . And are they worth holding on to?

Also,  this country is trillions of dollars in debt, can we really afford to spend/waste money on "painting" our currency.

Need answers please. Thank you!