What to give for a goodbye gift

I have been working for a Japanese company for 5 years. Two of the Japanese gentlemen I worked closely with will be leaving the United States to move back to Japan. I would like to give them each a gift to say goodbye and good luck. Perhaps something to remember their stay in the United States. I would like to know if there is something that is given traditionally for this occasion. Suggestions are welcome.

Maybe something that embodies our version of good luck - namely, a Luck Rabbit's Foot

Japanese often buy "omamori" or good luck charms from temples and shrines (while they are specific to which kind of luck they give like study, healthy childbirth, etc.) and this might be just as good.

Or:
-Native American 'Dreamcatcher' - those circular wooden webbed charms with furry tassels hanging off them, meant to catch bad dreams (so I hear)

How about taking a picture of the office staff (including them) and framing it? Or if you have pictures from office functions, you could make little photo albums or even scrap books for them. You can't buy good memories!