Typically, the employee who is leaving does not need to give farewell gifts. That would be a lot of gifts to purchase for every member of the office! However, I do not think it is a bad idea to prepare a small gift or a note of appreciation to your boss. It can be as simple as stating your gratitude for the opportunity to work. Before you leave the office and have to give up your work email, it may be a good idea to send one final email to all your colleagues, saying goodbye, wishing them well and sharing your personal contact information should you choose to remain in touch.