Who Would Do This To A Silver Coin?

I believe they used to nail coins to outside door frames to ware off evil spirits,but I thought this practise was a long time before that one was nailed

There were two traditional reasons for nailing a coin to a wall:

- good luck, as stated. As I understand it, this was often apparently done as a finishing touch to a completed building.
- a fake coin would be nailed to the wall to (a) remove it from circulation as required by law and (b) form part of a "reference collection" of fakes for a storekeeper to look out for.

Which one is more likely depends I guess on what kind of building it might have come from: a house/manor/barn would be good luck; a store or pub might be a counterfeit. And, of course, on whether or not that florin is actually made of silver.

The second one looks like it got hit by a plow.

If ever you're hunting old cellar holes always search around where the front door would have been. Also scan the actual foundation itself as people often hid coins between the stones up high. My first ever 1700s copper was found between the top two stones in a foundation. People would also put a coin dated the year of construction above the front door sometimes. I actually love coins that have been altered in some way. I have a half real that was turned into a cufflink