Have you ever heard of burying kitchen items in the ground for three days that have been made treif by accidentally using meat for milk, etc
No, I am unaware of such a concept. The closest thing that I heard of similar to this, is something called miluy viruy. If a utensil became trief because something was soaking inside it for 24 hours, then there one can fill the utensil, (i.e. bottle with water) and let it soak in the water for 24hrs. Then spill out the water and repeat this process three times, which would come out to three days, although not at one time.
There is another idea, that when a milchig knife cuts fleishig meat etc. and the food is not sharp, but there is a residue of fat left on the outside of the knife, that it can be removed by sticking the knife into the hard ground 10 times to remove the residue. However this is not commonly done nowadays for various reasons.
There seems to be a misconcetion that one can put a utensil into the ground for an amount of time and that would be considered kashering it. This is unfoiunded, see The Kosher Kitchen pg. 255.