Going through my grandparent's things, we found a signed baseball. We can't make out the signature, so we don't know who signed it. They were lifelong Cubs fans, so it's almost certainly signed by a Cub, and likely from the 1980s or earlier. The baseball was in a container with a caricature drawing that my grandmother likely put in there.
Here's a gallery with a few photos: https://photos.app.goo.gl/LHKQdDxYKGHC7byt9