Now this is a great post. I have no idea how I missed this one.
Not only is the treasure spectacular but it also demonstrates how treasures are forgotten and left behind.
Your grandpa totally forgot about this stash and this sort of thing has happened 1000's of times over and probably all the treasure buried will never be found.
In fact, I once owned a house and at the time I stashed money up above the basement ceiling (dropped ceiling). A few years later we sold the house and moved away. It wasn't until 2 or 3 years later that I even thought about that stash again. It was something like $1,000. My guess is it was found long ago.
People get stressed, older, etc., and they simply forget things. There's plenty of loot out there hidden in houses and/or buried in the back yard.
Badger