2-3 mm diameter, round white pill with a simple imprint/impression of 100 on one side. No other markings, no smell to it, not powdery so it's probably lightly coated or tightly bound. I suspect it's some manner of opiate/painkiller but need to know for sure before I go accusing a certain teenager. Thank you for any help you can provide!

Country of origin... I'm assuming the USA.