I understand your intentions were good, but I believe that the parents should be consulted prior to giving anything of value to a child that isn't essential for safety. (I wouldn't have a problem with the gloves, given that the childs hand were frostbitten, but I would have called them to let them know that the child would be wearing them home, and why.)
As a parent, it is unsettling to have your child receive something from someone whom you don't know well, or whose intentions you don't know.
A local businessperson recently sent a mailing to the students at our middle school inviting them to attend a party at which money and other prizes would be given away. My daughter showed it to me, and I went ballistic. I really didn't think that the guy had any nefarious intentions, but by sending the invites directly to the kids and not the parents, he seemed to be trying to circumvent the safety rules we have taught our kids (not accepting gifts or money from adults.)
That's probably not the best comparison, because your intentions were simply to provide for the child's needs, not to gain anything. But I can understand the parents' objections and don't think they are entirely unreasonable. If he is in need of basic school supplies (a backpack), is there an avenue to address that that allows the parents to give input? Perhaps they chose not to give him a new one because he did not take care of the one he had. Perhpas he destroyed his own backpack and they wanted him to earn the money to replace it. Perhaps they felt threatened by the new backpack as an indication that they are inadequate providers or feared that they would be reported to CPS. Perhaps they were truly concerned that he stole it. I honestly think that the dad's reaction, while not pleasant, is understandable.
A few years back, our family was seeing a therapist for problems with my DDs behavior. The school counselor, whom I consulted first, had not been helpful. Once we went into therapy, I sent an e-mail to the counselor asking that she NOT see my daughter without my prior knowledge, because she was giving information that contradicted with our therapist. After several weeks of therapy and marked improvement in DD's behavior, we saw a significant decline that we couldn't explain. I learned thru the grapevine that the school counselor was meeting with my daughter without my knowledge, and told her that "It was OK, because they were just having lunch." I'm sure I don't have to tell you what my reaction was. Regardless of the counselor's intentions, she violated my reasonable request, then left me to deal with the fall-out. Again, my example is probably a little more extreme than yours, but the father had already made his feelings known about giving things to his son, and you unintentionally violated that.
I think your best bet is to apologize, explain that you didn't mean to undermine his authority and keep that all in mind the next time this comes up.