Conversation so far:
When was Pet Sounds released?
In late 1965, Wilson began working on material for a new project, Pet Sounds.
What songs were on this project?
Wilson even toyed with the idea by releasing "Caroline, No" as a solo single in March 1966, it reaching number 32 on the Billboard charts.

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