What is this pill - with 'm' imprint?

I have been unable to find a match, 2 options:

Take the pill to your local pharmacy and ask the Pharmacist to assist you.

Call poison control at 1-800-222-1222.

Is it possible your pill is from Canada?

Your description is very similar to that of Mylan-Valsartan (valsartan) 320 mg (generic Diovan - which is used to treat high blood pressure) manufactured by Mylan in Canada.

Description: Each dark grey violet, oval shaped, beveled edged, biconvex film coated tablets debossed with "VN 4" on one side and "M" on the other side contains 320 mg of valsartan.