Where do our best ideas come from?

A correspondent writes to me:

Isn’t it weird that the best ideas we have just…. pop into your head? I have no idea how to trace them. They just show up.

@Tyler any research into this area?

Dean Keith Simonton springs readily to mind, noting he has a new book coming out this year on genius.  Here are some overview pieces on simultaneous discovery, and of course those tend to stress environmental factors.  Here are some approaches to the multiplicative model of creative achievement.  I am a fan of that one.  What else?