Weeds.

While the lack of rain has adversely affected many crops throughout the US, in my backyard it does not yet seem to have phased the weeds. 

I do not know much about weeds, other than being able to identify them and knowing you need to get them out by the roots (otherwise, they will just keep growing).  One great reason for planting your vegetables in neat rows is that it makes the weeds more readily identifiable.  I try to go at the weeds at least once a week, more if they seem to be really plentiful.  Here are a few of the most common (I hate all of them equally).