[roll] around in {one's} (mind|head)

to be thought about by someone without much coherence

Various ideas and possibilities roll around in my mind when I'm brainstorming.
The question of what to do next rolled around in her head, causing confusion.
Different options for vacation destinations rolled around in their minds as they planned their trip.
Worries and concerns about the future often roll around in my mind at night.
Random thoughts and memories roll around in his head as he tries to fall asleep.