Agreed with INeedCoffee that Clyde Englehardt at Toledo Coin is a fair dealer.
They could be worth a bit more if you have rare issues, but the historic spike in silver prices means you have some significant melt value in these silver dollars, which each contain .7735 ounces of silver. The melt value on Morgan/Peace dollars is about 25 times face right now, so with 15 silver dollars you have approximately $375 in metal alone.
Now, dealers have to make a profit, so do not expect on a melt exchange to get every penny. I would not take less than $20 per coin at the moment for melt value.
As far as numismatic value: some Morgan and Peace dollars are extremely rare, while most are quite common. The value of course depends on wear, and you need some expertise to properly grade these coins. This table provides mint totals for Morgan dollars, while this page provides mint totals for Peace dollars. As you can see, some of the rarest silver dollars are the Carson City (CC) mint issues. The mint mark position on Morgan dollars is above the letters DO in DOLLAR, on the back: