PH: Musical Postcards

Thanks to @shirleyinCA for the idea for this swap.

We all have more "musical' postcards than you think!

The obvious; a musical instrument somewhere on the card, Elvis, the Sydney Opera House, most birds sing, etc.
The less obvious theme: any San Francisco pc = "I Left My Heart in San Francisco"; flag of a country pc = their National Anthem; baseball stadium pc = "Take Me Out to the Ballgame". Lots of songs about rivers, rain, sunshine and love. Start humming a favorite tune and find a postcard that fits your song!

Send your partner four (4) postcards and a note telling what song fits each card or how the card depicts a musical theme.

Please send in an envelope. Postcards should be unwritten and unstamped. They should be store bought only and of good quality. (No handmade/freebie/ad/zazzle). Sender's choice.