Cheever's Accidence was an elementary Latin grammar, studied by students at Boston Latin School in the early colonial period.  According to John A. Nietz, in his book 
The Evolution of American Secondary School Textbooks, students also studied forms and syntax in more depth in Lily's 
Latin Grammar, practiced spoken Latin from Corderius' 
Colloquies and read 
Aesop's Fables in Latin.  You can find a copy of 
Cheever's Accidence at the 
Stepping Heavenward blog.  
The Classics Department at Holy Cross College has an extensive website, 
Latin in Early America, describing how the Classics were taught in the 17th and 18th centuries in America.