Just received $50 worth of Bitcoin from someone? I am not sure who has sent it to me and why but I just received $50 worth of BTC. How do I find out where it came from?

Accepting an anonymous payment may bite me in the behind later on. Is there an option to deny BTC payments?

Something to think about....
It's impossible to deny BTC payments, you have probably provided your btc adress somewhere. It's extremely improbable that they typed in your adress randomly.

Only reason why you should worry is if published your private information and an that btc adress. But in this case it's just $50 and you can keep it unless you would like to return it to the sender.