You can read her oral history, articles about her in places like Wikipedia, and many snippets in local early historians like J.W. Wood or Hiram Reid. Her son-in-law Miguel Blanco/Michael White devotes a chapter to her in his oral history.
According to family lore she was literate. Beyond this was a confidence that is apparent in her oral history and seems reflected in the lives of the women who were a part of her circle.
It is a profoundly proud woman who begins her oral history, "I, Eulalia Pérez..." It is a woman who was familiar to those who spoke English and those who spoke Spanish. In part because of her age and in part due to her amazing life, and her dedication to her work.
Eulalia Pérez de Guillén de Mariné died on June 8, 1878 four years after members of the Orange Grove Association moved to the land that had been known as Rancho El Rincon de San Pascual and eight years before much of the rancho was incorporated as the City of Pasadena.
Rasmussen - http://articles.latimes.com/1998/sep/06/local/me-20088