I cash my finds about once a year.
When I get them home I run them through the ultra sound machine and this removes most of the crud but not the corrosion.
for the bad ones
I boil the coins in vinegar for a few minutes and this cleans most of them enough to roll
I roll all the good coins and cash them in at my local bank. The bad ones I still roll but take them to the main branch of my bank where I tell them what they are. First time I did this they got really confused and could not understand why I would bury coins and dig em up. They take them and I believe they get sent off to be destroyed. The fed pays the bank back face. They know me now so everyone hides when I come in.