Lost vintage Mickey Mantle 1950s baseball card in protective sleeve near park in Omaha / Council Bluffs.

I lost a package containing a vintage baseball card from the 1950s while walking my dog around Omaha / Council Bluffs near the park. It features Mickey Mantle and is in very good condition, encased in a protective sleeve. I think I might have dropped it when I stopped to tie my shoe. It has significant sentimental value, and I'm really hoping to get it back.