Hi - haven't read all the replies, but I was wondering if your mom is close by - could you maybe have her keep the toy at HER house, as a special treat for your LO when he goes over there?
This is one of those issues I've thought a whole lot about. Growing up, people would usually get me things I didn't want, didn't like, didn't care about. Still today, certain folks want to get DS things that I think are pointless or useless or obnoxious, and really, sometimes I just want to cancel the whole gift-giving thing. In fact, I DID tell everyone I wasn't participating in gifts a few years running, but guess what? I got presents anyway. And yeah, most of them things I didn't want. To me it seems like a waste, but I understand deep down that giving those gifts makes the giver feel good, and I would NOT want to spoil that for them. I have always been a gracious gift giver AND receiver, and I can't imagine teaching my LOs any different.
I've also come around to reality on the toys situation. DH and I agree we want to limit toys, and we prefer to have toys around that encourage active or open-ended play, but we also know that not everyone sees it the same way, and we've figured out that exposure to "other" types of toys is not going to hurt him. (He's just going to covet those things at other kids' houses anyway - DH and I both remember THAT from our own childhoods.