It might have been Echo I. That was a big mylar balloon that was placed into orbit in the late 50s. It had a leak, so it didn't last but a few weeks. Pretty cool while it lasted. MC

I was just 3 and 1/2 years old, and although I have an early memory of going up Big Cottonwood canyon to see a satellite pass overhead (with my Mom) I think it was more likely Telstar or some other later satellite.