I found a pill in my son's room. It is white, oblong, and has no markings on it. it kinda looks like

This question is super old BUT I had a similar experience and totally panicked until I found the bottle and the rest of the pills. We had purchased a bottle of 800mg Ibuprofen pills for a toothache when traveling in Mexico. The pills are white, oblong, fat, have no imprints and no score. If you’ve been out of the country & bought medicine, that could be your culprit.

Tylenol

I see this question is very old, but I am going to answer anyway, in case someone else comes looking for an answer. All Rx and OTC drugs in the US are required by the FDA to have an imprint, otherwise it could be a vitamin, herbal, energy, diet, foreign or illicit.

It could be a number of different drugs. If you want to know if it's a controlled substance a good way of finding out is to purchase a drug test as a store (6 panel or even a 11 panel test) and put half the pill in either water or Urine (Urine is the best to use) and then use the drug test and it will show a positive for whatever type of drug it is most likely if it's a controlled substance and can be checked with a UA test. Hope this helps! Good luck to you. I hope you find out what it is.