Conversation so far:
When was Pet Sounds by the Beach Boys released?
Pet Sounds is the 11th studio album by the Beach Boys, released May 16, 1966.
What songs were on the project Pet Sounds by the Beach Boys?
Pet Sounds is arguably seen as a Brian Wilson solo album. Wilson even toyed with the idea by releasing Caroline, No as a solo single.

Question: He toyed with the idea of what?
Self-contained rewrite: Regarding Pet Sounds, Brian Wilson toyed with the idea of what?