It looks like a thread that broke off. I say that because in the second photo it looks tapered. Hard to guess the Diameter of what this came from since the bend radius appears tighter on the right side and opens up moving left on the top photo. Hopefully its from the pan plug bung or dipstick bung.
I highly doubt it is a valve seat as there is no real path for it to get in the
oil pan, unless PFM was at work.