Is there a way to track gift cards when the gift card and receipt have been thrown out?

I'm so mad. I had my baby shower Sunday and when I got back home, my cards and all the gift cards were missing from the gift bag they were all in. My husband and I asked around if anyone may have accidentally taken them home or put them somewhere for safe keeping. After some digging, my mother-in-law said that she thought they were "garbage" so she removed them from the box of gifts when she was helping load the car. She told us we should have been more careful, but I said, "Why would you throw out a gift bag full of cards without checking with us first?! It was already in the car. It was quite obviously in a box with the gifts and meant to be taken home" She said "I don't keep cards. They're garbage. You should have put them somewhere safe." I loaded the box with the gift cards into the car and I didn't expect someone to take the bag out once it was loaded!

I called the venue but their garbage had already been picked up early this morning, and my mother-in-law told us what she'd done today around noon.

So 1: is there anything I can do or #2, is it reasonable to ask her to replace the value of the cards? It would have been $325. I have a list of everything people brought written out for thank yous.

*** I don't believe she stole them. She just was very over zealous with cleaning and honestly, she just didn't think.

*** my husband and I have reached out to her as a united front and told her that she will be replacing the gift cards with cash. Originally she refused but we told my sister-in-law (husband's sister, mother-in-law's daughter) and she said hell no... You give them that money! My mother-in-law tried to say that it was an honest mistake and anyone could have done it so she shouldn't be held responsible. My husband told her this isn't an "oops, well that is inconvenient" moment. He said she needs to make it right. I'll never get the beautiful handwritten cards back, which was something really special. At least reimburse us for the gift cards!