I'm a lady ... so what else would you expect other than the kitchen sink...
A quick look finds:
purse
D lock
notepad
stickers
work folder/books
waterproof trousers
pump
gloves
flask
fleece - it was cold yesterday ... so I put it in as an emergency back up
first aid kit
warm hat - I could probably take that out now
sunscreen
a ride leaflet that I was given a week ago
sunglasses
more gloves
tissues
Var tyre lever and soma ones
Pens, pens and more pens ... I can never find one when I want cos of all the other junk
Lipsalve
Chocy bar emergency rations
Memory stick
Nail file
Repair kit - opps - just found a second one in there
2 phones
Another note pad
2 things for undoing nuts
Spare Allen keys - good set usually live in a pocket.
Lunch box
Then obviously other stuff gets chucked in on top ... last night I had my Orlieb pannier full to the very top of shopping, with the loaf of bread resting precariously on top ... I cycled slowly home having to repeatedly check it was there after each bump or corner.
And if it was winter there would other things ... like those handwarmer things, more spare layers and usually several lights chucked in and then lost.
As you can see I have an extremely empty light bag (well in my dreams I do

).