https://screenrant.com/true-crime-references-agatha-all-along/#:~:text=Mare%20of%20Easttown%20was%20lauded,creek%20as%20a%20%22crick.%22

Mare of Easttown was lauded for its use of the seldom-seen-on-TV "Delco" accent, a dialect of Philadelphia English spoken widely in the Delaware Valley. Agatha (https://www.hollywoodreporter.com/tv/tv-features/kathryn-hahn-talks-agatha-all-along-tribute-1236006312/) makes her own attempt at imitating this unique drawl, made obvious by her usage of certain words, like referring to a creek as a "crick."