Random nut found under van

So, I pulled my van into the driveway the other day and noticed a nut lying on the ground where the van normally sits. Any idea where I could start looking for missing nuts on the van? It has marking OF 181 on it if that helps at all.

I looked under the hood, and everything seems in order nothing missing that I can tell, but all the nuts under there are dingy and dirty and this one I found looks shiny and new. So, I'm wondering if this even came off the van at all?

I am going to borrow my neighbors' ramps and try to look under the van this weekend, I just don't know where to start looking.