"Cache Keeper" - anyone seen this?

Or is it just urban-legend type talk?

I have read this three or four places. I paraphrase below:

"One superstition was the cache keeper, where the person hiding the cache would put a large iron object, typically an old doorknob, on top of the cache to ward off evil spirits and keep the cache safe. Unfortunately, in the metal detecting world, it could work like that if someone is discriminating against iron targets"

Has anyone ever actually seen this, a cache found under a junk iron piece??

Inquiring Minds Want To Know!!

Thanks~

Doug