There are many songs from the era of early pop- define it yourself- which can be played on a basic melodeon or concertina & much more fun than many folk songs.
Sam cooke, Al Bowlly, Hoagy Carmichael, Lonnie Donegan, Dr Hook to name a few & did you ever hear Bob Davenport singing Memphis Tennessee or jim Bainbridge singing 'Rum & Cocacola' with his melodeon?