Many people remember the D*ck and Jane books. They were very common, but were eventually phased out, possibly because of those unfortunate associations. They were published by Scott Foresman.

When I was in elementary school, we were using the Macmillan readers featuring stories revolving around siblings Mike, Mary, and Jeff. They had a goat named Billy, a dog named Bolo, a cat named Velvet, and parents called Mother and Father. My husband, who grew up in California, remembers the Janet and Mark books by Harper & Row about the same time. Apparently they were used only in California schools.