She is best known for her role as Margaret Lanterman, the enigmatic Log Lady, in the David Lynch TV series Twin Peaks.

[3] Coulson met Lynch in 1971[4] and performed various behind the scenes functions during the four-year filming of his low-budget classic Eraserhead (1977).

Coulson played the role of Susie in Lundgren's film Redwood Highway with Shirley Knight, Tom Skerritt, and James LeGros.

Coulson was married to actor Jack Nance (who played Henry Spencer in Eraserhead, and Pete Martell in Twin Peaks) in 1968; they divorced in 1976.

Her second husband, Marc Sirinsky, with whom she had a daughter, Zoey (born 1987), is a rabbi, at one point resident at Temple Emek-Shalom in Ashland, Oregon.