After the Washington Post article was published, Mark Herlong was kind enough to email me the news links from 1883 about the Anacostan relics that were found during the construction of Garfield Park. They included skeletal remains and hair from a young Native girl. Here are the citations from the two original articles, from The Evening Star and the Washington Post. Copies can be viewed online by searching through the DC Public Library (and other public libraries) using the digital newspaper links:
Washington Post, Aug. 12, 1883 p. 8
"Some Curious Discoveries. An Indian Girl’s Skeleton and Other Relics of the Past."
Evening Star, Aug. 22, 1883 p. 1
"Indian Remains, Etc., Found. What the Workmen Grading a Public Reservation Have Dug Up."