Mechanical repair (all stashed in an old water bottle): Multi tool (lezyne 5?), tube, tire levers, patches

The day's clothes (minus shoes, which stay at the office)

Lunch, usually in a couple of baggies and a couple of small lock'n'lock

Glasses x 2 (clear and tinted, wear one, other goes in case)

Granola bar

Keys, wallet, cell phone

Lights, which of course don't live in the bag

Garmin edge 500, also on the bike