These are some of mine .
List form in no particlular order . Many more to follow !
Clouds - Love watching them sail past . I like to try and spot shapes or objects in clouds.
Sounds ..... even everyday things like drills or machinery - even repetitive hammering !
Indoor rainbows - when the sun reflects on a shiney surface and you can see all the colours on a wall or something.
Water ... everything about it ! The sound of sea tides or waterfalls , even the taste !
Pictures with straight lines in them ... parallel things etc
Pictures showing perspective.... like corridors or tunnels going into the distance.
More to come ! !
By all means ADD your OWN ideas .