My maternal grandparents gave each grandkid every year a crisp $2 bill and $1 bill. Every year, even through high school. And as someone else mentioned, it’s not like they were poor, so that’s not why. Heck, I would have settled for a little box of homemade Christmas cookies or something, or a small ornament.
My husband, being a letter carrier (in a very well-to-do neighborhood), sometimes gets presents as tips around the winter holidays. Most of the time, he’s simply grateful that they thought of him at all, but some are very odd or even insulting.
One year he got a CD of Celtic music (not even Christmas) from one customer. Since he’s obviously not Irish in looks or name, this puzzled him, but he was glad they thought of him at least.
One customer gave him a dollar bill in an unsigned Christmas card. This was one of the few times he was insulted, as he felt even a signed Christmas card would have been nicer in his eyes. Stuffing a single dollar in a card and not even bothering to sign his name seemed to him like such an afterthought.
One customer met him at the door the year before last, and told him, “We would have given you something, but we felt you let us down in your work performance in October and November.” His reply was, “Oh yes, that was when I was laid up at home with a broken shoulder and unable to work; I’m sorry the substitute didn’t do a good job” (which was true). He turned to leave as she stood there dumbly, and the lady came rushing out of her house about 30 seconds later with a $5 bill, no card or anything even. He told her he didn’t need pity and continued on his route.
A present that still puzzles us is a bottle of Cristal champagne; at the time, it cost well over $100 for that vintage (we checked in a store). He didn’t recall saving the life of the customer/his kid/his dog/etc., so his best guess was that the person had received it as a present, not known its value, and regifted it - either that or he knew its value but didn’t care. We happily drank it, not minding if it was regifted. 
Like mnemosyne said, phone cards can be darned handy. I used one within the last several months when I was stranded and my cell phone’s battery had died. My husband has received at least one of these, and keeps it as a “just in case” backup.