Grok worked well once I had enough information to form a cogent question.
McGuffey’s Eclectic Primer (or simply McGuffey Eclectic Primer) — introductory level, often for pre-K to grade 1.
McGuffey’s First Eclectic Reader (or McGuffey’s Eclectic First Reader).
McGuffey’s Second Eclectic Reader (or McGuffey’s Eclectic Second Reader).
McGuffey’s Third Eclectic Reader (or McGuffey’s Eclectic Third Reader).
McGuffey’s Fourth Eclectic Reader (or McGuffey’s Eclectic Fourth Reader).
McGuffey’s Fifth Eclectic Reader (or McGuffey’s Eclectic Fifth Reader).
McGuffey’s Sixth Eclectic Reader (or McGuffey’s Eclectic Sixth Reader).
As luck would have it the entire collection is at Gutenberg. https://www.gutenberg.org/ebooks/author/5671
In this instance the titles were simple enough and basically incremental in their titling. That is not always the case.