The only thing I ever really leave home with is a padlock and a key for the dingy.
2 fully-charged cellphones / mobile phones (on different networks)<br />
Money - including coins for parking, Credit card, pen, paper <br />
AA card (that's automobile association, like AAA - not Al Anon)<br />
Tissues, brolly, anorak<br />
.. and round here at this time of year<br />
wellies, snow brush / ice scraper, snow shovel, road grit / salt, hat, gloves, fleece