Pierce Mill, Rock Creek Park's most prominent historic feature, is situated on the west bank of Rock Creek a quarter mile below its confluence with Broad Branch. Built in the 1820s by Isaac Pierce and his son Abner, the granite structure is the only one standing of several mills on Rock Creek in the 19th century. The park commission acquired the mill property in 1892. The mill continued to grind corn and grain, until 1897, when its main shaft broke.
About 1905 the Board of Control permitted Mary Louise Noble to operate a tea house concession in the picturesque building, to which an enclosed frame porch was added on the upstream side. Florence I. Blake of the Dolly Madison Candy Company succeeded her a decade later, but the Office of Public Buildings and Grounds ousted Mrs. Blake in October 1919 for providing poor service and failing to pay her $60-per-month rent promptly. Hattie L. Sewell, a black woman, obtained the concession for $45 a month in 1920. Her presence prompted complaints from E. S. Newman, a prominent park neighbor and trustee of the Pierce-Shoemaker estate, who saw the place becoming "a rendezvous for colored people, soon developing into a nuisance." Colonel Sherrill told Newman that he had received no other complaints and that under Mrs. Sewell the tea room's service had been satisfactory and business had increased. 
Newman persisted. Doubtless as a result of his influence, Sherrill advised Mrs. Sewell that her contract would not be renewed in October 1921 and that the tea house would be turned over to the Joint Welfare Service, which would use the proceeds for charity. This arrangement had not been cleared with the Joint Welfare Service, which declined to take the concession. Sherrill then induced the Girl Scouts Association of the District of Columbia to fill the role. It began its service in November 1921, boosted by publicity from Public Buildings and Grounds. "A delightful air of hospitality will be found always in evidence at the tea house, as the management is directly under a large committee of ladies prominent in Washington society and there will be some one of these actively in charge each day," Sherrill announced in a press release. Among the specialties offered were "Harding waffles," honoring the incumbent president. The Girl Scouts Association was allowed to use the second floor of the mill as living rooms for the attendant in charge. 
Asked to justify for the record the absence of competition in selecting the new concessioner, Sherrill provided a statement at sharp variance with his initial reply to Newman:
Competition was not deemed advisable in letting this concession because of the fact that it would be impossible to select or obtain in that way the type of proprietors desired. The party who operated the tea house prior to this concession was the high bidder in a competition. A great many complaints were received and a large number of people stopped patronizing the place. In order to overcome the prejudice which had grown up it was thought best to select the proper party who would operate the establishment to the best interest of the public and of the government. 
For unrecorded reasons the Girl Scouts Association did not long continue to run the Pierce Mill tea house, and the Welfare and Recreational Association of Public Buildings and Grounds, Inc. (successor to the Joint Welfare Service), was persuaded to take charge. It held the concession until 1934, when the mill ceased to function as a tea house.
In 1919, the last year of Florence Blake's deteriorating operation, Colonel Ridley had instructed Horace W. Peaslee, an architect on the Public Buildings and Grounds staff, to investigate the possibility of restoring Pierce Mill in appearance if not function. Pierce submitted his report that November. He favored upgrading the structure as a restaurant featuring al fresco dining, with some old mill components replaced for atmosphere:
The restoration of the mill feature in part brings up the question as to whether or not it would be well to attempt, for the sake of historical record, to put back, without competing with the new function of the property, the essential parts of an old-time mill. Enough could be readily obtained or reconstructed to connect up the main working parts and the effect would be right, whether or not the wheels were continuously turning The first impression of the problem was not favorable to the attempted restoration of the mill-wheel as the last wheel used was an unpicturesque turbine, and the reconstruction of the preceding undershot wheel would leave it high and dry, fanning the air without any possible water-weathering or suggestion of a past. With detailed study, it is believed that the wheel could be restored if made apart of the proposed general restoration including necessarily a flume, race and spillway, partly following the old lines and partly conforming to and strengthening the new design. 
No action was taken on Peaslee's recommendations, nor was another proposal two years later adopted. Warren J. Brown, a local entrepreneur, then suggested to the Office of Public Buildings and Grounds and the Commission of Fine Arts (which reviewed the aesthetics of government projects), a fully operational restoration of Pierce Mill; he would run it and sell the ground meal. Charles Moore, chairman of the Fine Arts Commission, responded by advocating the treatment Peaslee had recommended. Colonel Sherrill wrote Brown, "It seems to me that from a business standpoint it would be a most unprofitable undertaking for you, and could not fail in my opinion to detract from the attractiveness of it."  When the mill came under new management in the 1930s, however, Brown's vision would prevail.