They usually have bags of nuts at the buffet, on one end - I grab some for the plane. Last trip, I was at the airline line too long so didn't have much time in there. Luckily, I had my thermos cup (about 24 oz), ordered a couple of tall drinks, poured them in to take to the gate and on the plane. Also had some zip lock baggies and put some snacks in for later as well. I think it would be discouraged, so I packed away discreetly at my table (picked one off in an out of the way area).