Right now you can use the search bar within Google Mail to easily search for an email. This is what mine looked like the last time I searched my inbox:
Google is introducing a new feature that will allow you to search across your Google Drive as well as email.
This is what the search results will look like once Google has updated our accounts. You will be able to see relevant Google Docs at the bottom of the search window.
This new feature will be released within the next week and should make it easier to quickly locate a file or email.