I found a small, oval pill with 377 on one side and nothing on the other, what is it?

I would suggest taking it to a pharmacist and asking them?

Don't take it for sure, if you don't know what it is.

Excellent answer above in recommending taking the pill to a pharmacist for identification!

You might also want to check out the information that you might find on the following site or take it to a pharmacist for identification and disposal. The site is good, but not foolproof. But, to be sure, I would take it to a pharmacist. Anyone answering you here as to what it might be, runs the risk of the ramifications if they answer and are incorrect no matter what you say the reasons are as to why you are asking.

Below, is the site to which I am referring:

Pill Identifier - Drugs.com