Deleted custom fields and their data are stored until your organization permanently deletes them or 15 days has elapsed, whichever happens first. Until that time, you can restore the field and its data. However, the field still counts against the maximum number of custom fields allowed in your organization.
Nov 13 2014 08:18 AM
Recycle Bin -- Holds the Deleted Record
Deleted Fields(on every object) -- Holds deleted fields.