Zora Neale Hurston did a lot of ethnographic/anthropological work during the WPA era. Her book Mules and Men is mentioned in that thread, along with a link to an online version of the text.

She's best known these days for her novel Their Eyes Were Watching God, that uses a lot of material about the culture of the day and the unusual yet realistic nature of the community she describes. She's also known for having more or less disappeared from view for years, ending up a housekeeper and buried in a pauper's grave until Alice Walker took an interest and revived scholarly interest in Hurston.