Question: Mound of Butter is a painting by the 19th-century by which French realist painter, made between 1875 and 1885, the painting is hosted at The National Gallery of Art, and its attached Sculpture Garden, is a national art museum in Washington, D.C., located on the National Mall, between 3rd and 9th Streets, at Constitution Avenue NW?

Context paragraphs:
National Gallery of Art Sculpture Garden: The National Gallery of Art Sculpture Garden is the most recent addition to the National Gallery of Art in Washington, D.C. in the United States.  It is located on the National Mall between the National Gallery's West Building and the Smithsonian Institution's National Museum of Natural History.

National Museum of American History: The National Museum of American History: Kenneth E. Behring Center collects, preserves, and displays the heritage of the United States in the areas of social, political, cultural, scientific, and military history.  Among the items on display is the original Star-Spangled Banner.  The museum is part of the Smithsonian Institution and located on the National Mall at 14th Street and Constitution Avenue NW in Washington, D.C.

Mound of Butter: Mound of Butter is a painting by the 19th-century French realist painter Antoine Vollon made between 1875 and 1885.  The painting is hosted at the National Gallery of Art.  The "New York Times" called the painting one of "Washington’s Crown Jewels".

National Gallery of Art: The National Gallery of Art, and its attached Sculpture Garden, is a national art museum in Washington, D.C., located on the National Mall, between 3rd and 9th Streets, at Constitution Avenue NW.  Open to the public and free of charge, the museum was privately established in 1937 for the American people by a joint resolution of the United States Congress.  Andrew W. Mellon donated a substantial art collection and funds for construction.  The core collection includes major works of art donated by Paul Mellon, Ailsa Mellon Bruce, Lessing J. Rosenwald, Samuel Henry Kress, Rush Harrison Kress, Peter Arrell Brown Widener, Joseph E. Widener, and Chester Dale.  The Gallery's collection of paintings, drawings, prints, photographs, sculpture, medals, and decorative arts traces the development of Western Art from the Middle Ages to the present, including the only painting by Leonardo da Vinci in the Americas and the largest mobile created by Alexander Calder.

Pennsylvania Avenue National Historic Site: Pennsylvania Avenue National Historic Site is a National Historic Site in the city of Washington, D.C. Established on September 30, 1965, the site is roughly bounded by Constitution Avenue, 15th Street NW, F Street NW, and 3rd Street NW.  The historic district includes a number of culturally, aesthetically, and historically significant structures and places, including Pennsylvania Avenue NW from the White House to the United States Capitol, the Treasury Building, Freedom Plaza, Federal Triangle, Ford's Theatre, the Old Patent Office Building, the Old Pension Office Building (which now houses the National Building Museum), Judiciary Square, and the Peace Monument.

National Aquarium in Washington, D.C.: The National Aquarium, Washington, D.C., was an aquarium in Washington D.C. It was located in the Herbert C. Hoover Building (owned by the General Services Administration), which is bounded by 14th Street NW on the east, 15th Street NW on the west, Pennsylvania Avenue NW on the north, and Constitution Avenue NW on the south.

Vero Beach Museum of Art: The Vero Beach Museum of Art is located at 3001 River Park Drive, Vero Beach, Florida.  It houses regional, state and national art exhibits and includes a sculpture garden.  The Vero Beach Museum of Art is the principal cultural arts facility of its kind on Florida’s Treasure Coast.  The accredited art museum includes art exhibitions, a sculpture garden, studio art and humanities classes, exhibition tours, performances, a museum store, film studies, an art research library, workshops and seminars, children and youth events, and community cultural celebrations.

National Portrait Gallery (United States): The National Portrait Gallery is a historic art museum located between 7th, 9th, F, and G Streets NW in Washington, D.C., in the United States.  Founded in 1962 and opened to the public in 1968, it is part of the Smithsonian Institution.  Its collections focus on images of famous Americans.  The museum is housed in the historic Old Patent Office Building, as is the Smithsonian American Art Museum.  The two museums are the eponym for the Gallery Place Washington Metro station, located at the corner of F and 7th Streets NW.

Dupont Circle: Dupont Circle is a traffic circle, park, neighborhood, and historic district in Northwest Washington, D.C. The traffic circle is located at the intersection of Massachusetts Avenue NW, Connecticut Avenue NW, New Hampshire Avenue NW, P Street NW, and 19th Street NW.  The Dupont Circle neighborhood is bounded approximately by 16th Street NW to the east, 22nd Street NW to the west, M Street NW to the south, and Florida Avenue NW to the north.  The local government Advisory Neighborhood Commission (ANC 2B) and the Dupont Circle Historic District have slightly different boundaries.  The circle is named for Rear Admiral Samuel Francis Du Pont.

Federal Triangle: The Federal Triangle is a triangular area in Washington, D.C. formed by 15th Street NW, Constitution Avenue NW, Pennsylvania Avenue NW, and E Street NW.  Federal Triangle is occupied by 10 large city and federal office buildings, all of which are part of the Pennsylvania Avenue National Historic Site.  Seven of the buildings in Federal Triangle were built by the U.S. federal government in the early and mid-1930s as part of a coordinated construction plan that has been called "one of the greatest building projects ever undertaken" and all seven buildings are now designated as architecturally historic.  The Federal Triangle Washington Metro station serves Federal Triangle and the surrounding area.

Supporting paragraphs: Mound of Butter National Gallery of Art
Answer: Antoine Vollon