How generous is your MIL?

My sister's MIL is wonderful to her and their kids. Whenever she is at the store and I see her she shows me all the stuff she's picked out for my sister's kids. My sister is really appreciative and I'm very happy for her. With my MIL it's whole 'nother story. Ironically, my MIL is pretty wealthy. By no means am I looking for handouts because my kids aren't relying on charity, it's just I thought all grandma's liked to buy their grandkids stuff. I hear stories of parents worried how their grandparents will spoil them. Like today she brought over a gift for my 1 year ol daughter's b-day. It was a small gift (a plate and toddler fork and spoon) and when she left she asked for the gift bag back. Last year for christmas she bought her other son's twins each a pretty big gift. And ironically again, her son is also wealthy. I'm upset that she doesn't treat the grandkids the same. Maybe she just doesn't like me and takes it out on my kids. We're 32 wks. pregnant and due in Sept. Not once has she asked if we need anything. My side has asked repeatedly. I'm very grateful they ask and always say I don't need anything. So greed is not the issue here. Does anyone understand what I am going through? How does your MIL act?