I have found all manner of mummified critters and bones in my travels, though I admit that I do seek them out for art projects. Old barns and abondoned houses are great places for finding such things. Even what seems like a damp basement or weather exposed place can have the dried up animals.
Last week I found a thumbnail sized bloody blob in the snowy chicken pen. At first I thought somebody fell victim to frostbite or a fight, so I did a comb and wattle check. All clear. So upon closer inspection, I saw that the object was a frozen mouse skull, with all the gunk still on but the fur. I have no clue how it died or what happened to the rest of its body.