Down on the Mall, this is the Smithsonian "Castle", with trees and a merry-go-round in the foreground. Toward the left, you can see a jet coming from Washington Ronald Reagan Airport.
Around 10:00 a.m., the sculpture garden opened. Near the southeast entrance is Four-Sided Pyramid.
Continuing westward, I walked past Moondog and Cheval Rouge (Red Horse).
Partially seen in the background of Cheval Rouge is Graft, a tree made of stainless steel.
For more on the garden and the specific sculptures, go here and here.