ForTce said:
Moreover, this will show you are lazy to find a nice gift.
Not necessarily, especially if you personalize the card to the person.
When I needed LORs for pharmacy school, I asked my thesis advisor from grad school and a postdoc I had worked closely with. I had moved away from the Bay Area, so it was very easy to enclose a gift card when I mailed them the materials. I think it would have been more awkward for me to mail a big box and for them to receive it. The card was discreet.
Anyway, back to personalization: for my prof/advisor, I got her a card for Trader Joe's. She likes to cook, loves to travel and try new foods, and always threw picnics and cookouts for our lab. I got the postdoc a gift card for eBay, because we would always look for bargains on eBay while waiting for our experiments to do their thing. We even bought supplies from eBay for some crazy experimental design we had. In each case, the card brought back fond memories and was not generic at all. Plus, I knew each of them very well, which is not always the case for LOR writers.
A Sears or Target card would be a little tackier and less personal. Oh, and I did
not buy a gift for my 3rd LOR writer, my manager from an office job I had, because I did not know her very well.
When I was in college and applying to grad school, I had my profs write my letters before the Christmas break because I was travelling to the UK over the holidays and would need to mail my apps earlier than the Jan. 1 deadlines. I brought a cool handblown Scottish paperweight back for each of them.