How can one add attachments from Google Drive in Gmail android app? In menu to attach file, it sometimes shows Drive as an option under recent if you have opened Drive recently. But other times it doesn't show Drive as an option to select from and then I couldn't find a way to select Google Drive. I am using Nexus 4.
You could open Drive-App, select the file you want to send, long-press on it and choose "Send".
There you can choose gmail and it automatically creates a new mail with the file attached.