Android Dumpstate Crash Logs Appearing Randomily
It seems you are accidently triggering the generation of a bug reports, as described on this google support site (click on the nexus link):


  Generate a bug report immediately:
  Press Volume (in between Up and Down) and Power at the same time (after a >significant delay -- up to a minute -- the device will vibrate if successful and open a new message in Gmail).


In my case, my device had a case which was triggering the bug report by inadvertently pressing 'volume' and 'power'