This white, round pill imprinted with M D9 is a doxazosin (as doxazosin mesylate) 1 MG Oral Tablet, per the NIH.
Doxazosin is a human prescription drug. The active pharmaceutical ingredient is doxazosin mesylate and is classified as, "Adrenergic alpha-Antagonists [MoA], alpha-Adrenergic Blocker [EPC]."
This pill is made by a total of 6 firms: (1) Mylan Institutional Inc., (2) REMEDYREPACK INC. , (3) Mylan Pharmaceuticals Inc., (4) Physicians Total Care, Inc., (5) Cardinal Health, and (6) NCS HealthCare of KY, Inc dba Vangard Labs
There are 14 other white pills that with a similar imprint: "M D9". They may be a different dosage of the same drug or a different drug entirely.