The National Park Service is seeking volunteers to work with third-graders this spring at its Frederick Law Olmsted site on Warren Street. The agency’s “Good Neighbors: Landscape Design and Community Building” program needs adults who can provide 10 to 20 hours per week from April to June. The program, open to students from Brookline and several Boston public schools, seeks to foster appreciation of the physical, social, and psychological value of public parks. The Olmsted National Historic Site was the home and office of the 19th-century landscape architect whose celebrated designs included Boston’s Emerald Necklace as well as Central Park in New York City. Anyone interested in applying should contact Brianne Cassetta at 617-566-1689, ext. 238, or by e-mail at Brianne_Cassetta@nps.gov.