You're not alone. My MIL has this insane habit of giving us random things from around her house OR giving us things that we gave her in the first place. My husband used to flip out every time she would come visit. Do we have out all the things she gave us? No, we do not. Because I didn't want her used crap from her house or re-gifted items we gave to her. And that was all before we had kids! He finally realized that it wasn't healthy, nor was it ever actually going to happen that we would keep and display all the stuff she gave us. Most of it ends up getting donated.
Finally with the kids, they've listened. After a few years of getting stuff the kids didn't play with or want, we told them they could either listen to us when we told them what the kids wanted (and we were ok with them having), they could send us cash/check and we would use it to give the kids gifts from them - basically we'd be their personal shoppers (they don't live near us), or they could give the kids what they wanted to get them, but not get upset if the kids had no interest, didn't play with it, and it ended up getting donated or sold within a month. They HATE giving cash or gift cards, so that's how we've had to approach it with them. Now they ask ahead of time when birthdays/Christmas come, and we usually have an
Amazon wish list or an idea of something unique they could do for the kids. My MIL sews, so my daughter always appreciates clothes for her AG Dolls. It's a unique gift that doesn't cost her much, but my daughter adores. Win for everyone.
With my family, they usually send cash and I can either purchase something for the kids, or give them cash. My kids LOVE to get cash or gift cards and save up for something they really want. Often, we pool it and get a membership to the zoo or take them to do something special. We're sure to let them know whose gift made it possible to do those things, and they get it. We do the same for my nieces/nephew at Christmas - this year we gave experiences or something they needed. My sister just got a new camper, and my niece & nephew needed a few things to keep in the camper, so at my sister's request, that's what we got them. Now they ask to go play in the camper to use their gifts. Ha!