Major Matt Mason was a line of action figures, created in the late 1960s and early 1970s by Mattel. "Matt Mason" was an astronaut who lived and worked on the Earth's Moon.
Samantha Carter told Charles Kawalsky that she played with Major Matt Mason "dolls" when she was kid, though she may have been being sarcastic at the time. Ironically, one of the action figures in the line had the surname of "Carter." There was apparently one version that came with, or possibly was sold as a separate accessory, a flying backpack, which Louis Ferretti inquired if Carter had ever owned one. (SG1: "Children of the Gods")