The Sixties were a pretty sunny decade when it came to pop music, as these relatively obscure tunes demonstrate:
The Millennium: Some Sunny Day
Skeeter Davis: Summer Sunshine
Hearts And Flowers: Try For The Sun
See also: Margo
Further research: The Millennium: here and here, Skeeter Davis: here, Hearts And Flowers: here and here.
Five Good Covers: Ode to Billie Joe (Bobbie Gentry)
18 minutes ago