my mother in law is very similar and attempts to gently suggest not to buy so many things is in vain. my husband and i are on the same page, which seems important. i don't think that ignoring the issue so as to avoid the "trickiness of MILs" is the best idea, as you will come across other issues like this when your daughter is old enough to notice and, say, be attached to the toys that get given that you are not excited about. also, sacrificing your values so as to avoid conflict/please others isnt a good excuse to not raise your child how you want to. i'm reading people responding to not address the issue or wait for some years, but all that happens in my opinion is that more patterns get established. grandmothers in particular often do have a very difficult time understanding that the baby is NOT their child, they are NOT mother again, etc.. While that may be an issue you don't want to touch on, it also might be unaviodable, and this is YOUR child and YOUR family. So it is my best suggestion to act with that confidence in you, and to act with the thought of establishing patterns that you and your spouse want to live with. after all, the more the pattern gets set, the harder to change (also the more your MIL has grounds to say, "well its been fine for so long! why do you have a problem now?!)
if we are given gifts when we are at my in-laws, we just leave them in the trunk and go right by the salvation army donation bins. we have one wicker basket that, which i have stated multiple times, is the capacity of the toys that our house will have. i stick by that and have realized that I do not have to be ashamed or feel like i am being disrespectful for throwing out the toys. what is disrespectful is not listening to that we do not want the toys!
the amazing thing is that my in-laws have never made any statement about that all the toys are nowhere to be seen. if they do, i will reiterate our value. the lack of commenting combined with the consistent behavior makes me think that the compulsive giving is what matters to my MIL, not what we do with the things. also, the suggestion that the money go elsewhere has not tailored the gift giving, as there seems to be an inherent self-gratification that goes with the buying of the things.
while we hope that someday they will "get it" and respect us, or atleast notice that our house is NOT getting more cluttered, we are unwilling to live with the day-to-day consequences of the buying.
we are considering not attending christmas with either side of our families because of this consumerism. we are thinking of going on an immediate-family vacation, as our kids are going to start becoming attached to the toys soon, and we will be the "bad guys" for taking them away. as with all things, we figure that even with communication, we cannot change others' behavior, but we can determine ours and stand by our boundaries/values.
Also, if there are ever any noisy toys, we leave them at my in-laws. then when the kids are playing with them and we can't hardly talk, i can hope that they will someday get why we do not want the noise in our home!
again, it is NOT disrespectful if you consistently are getting rid of toys bought for your child; what IS disrespectful is continuing to not listen to you or allow you the freedom to raise your child how you would like. soon your daughter will become attached to the toys, and it is a good idea to have your pattern established now.