These striking shots of two young women chilling out with some herb while relaxing sur l'herbe are official federal government photographs, captured in 1973 by a photographer on assignment for the newly formed EPA.
These photos come from the U.S. National Archive.
From a post about them on Vintage Everyday, a wonderful tumblog:
In the 1970s, the newly created Environmental Protection Agency commissioned nearly 100 photographers to document environmental issues around the country.
Marc St. Gil was assigned to record images related to the water and air pollution crisis in the area around Houston, Texas. While snapping photos in the Cedar Woods of Lankey, Texas, he happened upon several young people enjoying nature — and some marijuana. Instead of having them arrested, St. Gil captured some very candid shots of the pot smokers.