Lynn Anderson -- Mug Shot Shockface! 1970s Country Star Popped for DUI

Grammy winner Lynn Anderson -- who had a string of hits in the 70s and 80s -- was arrested early Friday morning for DUI after a car accident in Nashville.

According to cops ... Anderson said she'd mixed alcohol and Rx meds before crashing her car.

The 66-year-old singer -- most famous for "(I Never Promised You a) Rose Garden" in 1971 -- has had a couple of previous DUI arrests ... and spent some time at the Betty Ford Center.

She was released on $5,000 bond.