Paintings of the great outdoors by American artist George Benjamin Luks (1867-1933). Ashcan school.

"Holiday on the Hudson." ca. 1912.
“Holiday on the Hudson.” ca. 1912. Oil on canvas. Collection of the Cleveland Museum of Art. via commons.wikimedia.org/wiki/File:%27Holiday_on_the_Hudson%27_by_George_Luks,_c._1912.JPG
"The Swan Boats." ca. 1922.
“The Swan Boats.” ca. 1922. Oil on canvas. Sothebys. via commons.wikimedia.org/wiki/File:The_Swan_Boats_by_George_Luks.jpg.
"Verdun, France." ca. 1915.
“Verdun, France.” ca. 1915. Watercolor on paper. The Phillips Collection. via commons.wikimedia.org/wiki/File:George_Luks_-_Verdun,_France_-_Google_Art_Project.jpg.

These images are all in the public domain, “The Swan Boats” being in the public domain in the United States because its creator died before 1948.

Richard Edward (Emil) Miller (1875– 1943). American Impressionist.

"The Parasol." 1913.
“The Parasol.” 1913. Collection of the Minneapolis Institute of Art. In the public domain in the United States because the artist has been dead longer than 70 years. via commons.wikimedia.org/wiki/File:Richard_E._Miller_-_The_Parasol_-_2012.85.1_-_Minneapolis_Institute_of_Arts.jpg and http://godsandfoolishgrandeur.blogspot.com.
"Scarlet Necklace". No date.
“Scarlet Necklace”. via arthive.com. In the public domain.
"Arranging Flowers"". 1910.
“Arranging Flowers”. 1910. Private collection. via the-athenaeum.org. In the public domain.
"La Toilette". ca. 1910.
“La Toilette”. ca. 1910. Collection of the Columbus Museum, Columbus, Georgia. via commons.wikimedia.org. In the public domain.