There's no "R" mint mark. The mint mark position on a Seated Liberty half should be below the eagle. If the "R" is elsewhere your coin has been altered and has lost most of its collector value. If the R is where the mint mark should be please check it with a good magnifying glass.
There's more information at the Related Question.
The last year Carson City struck Seated Liberty halfs was 1878
A half dollar.
A US liberty 1936 half dollar is worth half a dollar in 1936. It is now worth around $15 to $50 or more in 2013. The variation depends on the coin's condition.
It's a common bicentennial half dollar, worth 50 cents.
A US liberty 1936 half dollar is worth half a dollar in 1936. It is now worth around $15 to $50 or more in 2013. The variation depends on the coin's condition.
It's a Walking Liberty Half Dollar not a Standing Liberty half dollar and the value is about $6.00
The coin is a Franklin half dollar not a Liberty half dollar, and is so common if it has any wear at all the value is for the silver only, about $10.00
A 1860 Liberty Seated Half Dollar in good condition (G4) is worth: $250.00.
A Liberty Seated US half dollar from the San Francisco Mint dated 1878 is rare, circulated coins start at $20,000.00 and go over $70,000.00. Many counterfeits exist.
A 1921-S Walking Liberty Half Dollar in very good condition (VG8) is worth: $80.00.
It's a half dollar, not a dollar, and it's worth at least $12.
50 cents.