FamousAppalachian Spring ChordAppalachian Spring, 1944 · Aaron Copland
Two chords at once: E major over A major
The slow opening (introduction of the characters): an A major chord with an E major chord laid over it, sustained softly as the music unfolds
Appalachian Spring opens with a hushed, glowing chord that seems to sum up wide American open spaces. Copland made it by placing an E major chord on top of an A major chord, which together give the five notes of A major ninth. On guitar, x06600 gives all five notes with one easy grip; 542100 stacks them as Copland did, A major under E major, for those who can stretch.
Also called Copland chord, Copland's polychord
Sources: Polychords, in Music Theory for the 21st-Century Classroom (Robert Hutchinson, LibreTexts) · Stanley V. Kleppinger, 'Copland's Fifths and Their Structural Role in the Sonata for Violin and Piano', Music Theory Online 17/2 (2011) · Aaron Copland's American Vision (NPR, Rob Kapilow, 2009)