In looking through issues of Nancy I see they also had some Peanuts comics as a back-up. Dell was also publishing a Peanuts comic around the same time. These all-new stories were not by Charles Schulz. Though he never had any assistants on the strip itself, he would often use them for ads and comic books. I think these were done by Dale Hale. 500 pixels was the biggest scan I could get of the first one.
This one is from #146, the September 1957 issue of Nancy
From #147, October 1957
From #148, November 1957
Unrelated but "Schulz" seems to be as commonly misspelled as something like plurals with an apostrophe s. Those who do it should have their hands broken.
Test - GoDaddy might be having another nervous breakdown, so I need to see whether this works.
43 minutes ago