Reese Witherspoon was an early champion of “Where the Crawdads Sing,” a coming-of-age story, romance and courtroom drama about a young girl growing up alone in the marshes of costal North Carolina, and set out to make a feature film with the help of screenwriter Lucy Alibar and director Olivia Newman. The film, starring Daisy Edgar-Jones as Kya and Taylor John Smith as her friend and first love Tate, was filmed on location around New Orleans, which presented some unique challenges, but all agree it was worth it in the end. The marsh is a character as important as any in the book. The film opens in theaters Friday.