Found: Attic Value: $3,000,000 The idea of finding invaluable baseball cards has always been an unattainable pipe dream for many American treasure hunters. That exactly what Ohio siblings Karl Kissner and Karla Hench discovered though, after coming across a box while clearing out the attic of their late grandfather's house. The box contained 700 cards dating as far back as 1910, in what has been named the most incredible discovery in baseball card history. In total, the collection has been valued at an estimated $3 million; the most expensive single lot of baseball cards ever.