Did I do wrong?

My class had a celebration and there was food and drink. I wanted to bring a little something to my mom, but there was nothing much left but some chicken chunks so I brought her some in a sandwich bag. She made me wish the party had never happened, saying that I had fairly treated her like a dog, bringing scraps. I never intended that at all, there just wasn't anything much left and I wanted to bring her SOMETHING. She said I should've taken something for her when I took for me, but my thoughts are, is that fair to the class who should've had first dibs? I mean, if everyone thought "Let me take some to my kids, spouse, etc., there wouldn't be enough for the class who even contributed home-prepped foodstuffs and $. So, did I do wrong? Does my mom have a legitimate cause to be offended? Am I wrong in feeling that the class had priority, and that it would've been wrong to take food to bring home when the rest of the class was still eating from it? I meant no insult; I really meant well, and now I just feel sick and sad. And I threw the chicken out to the stray cats. I don't want it after that. It's a matter of principle for me to know. Thanks.