What is the value of a 1979 silver dollar?
These coins are not rare. They're made of copper-nickel like dimes and quarters, rather than silver. Unless they are uncirculated or proof they are worth $1.
Although older silver dollars (1794-1935) all have a symbolic bust of Miss Liberty of different types on the front of the coins, no US one dollar coin is called just a "Liberty" dollar neither are the modern dollars (1971 to date) which do not have Miss Liberty on them. By the date 1979 your coin is a Susan B. Anthony dollar and none of the SBA Dollar coins struck for general circulation (except the 1979-P…
Please check your coin again. The last Peace dollars were struck in 1935. They were big (38 mm) coins made of 90% silver. A 1979 $1 coin is smaller (26.5 mm), carries a picture of Susan B. Anthony, and does not have the word "Peace" on it anywhere. In any case, a 1979 Anthony dollar that you got in change is only worth face value.