What to do with food leftovers from meals i buy during lunch?

Hey, I always see people at union station asking for food/money and I try to bring snacks or cash for them but during lunch i sometimes get food that I can't finish and i usually throw it out. but sometimes it's like fries which I could pack up and give to someone because I don't touch the fries that I don't eat/take a bite out of them. Maybe that's still gross but I was just wondering if I could do anything with it other than throw it out/take it home? I work in the financial district on like the td/scotia plaza side so something close to there would be convenient. Let me know if u guys have any ideas/thoughts. I try to finish my food but i have a low appetite if i'm stressed with work so I just cant finish the large meal portions that most places serve.