I may sound a bit cynical here, but then, I don't really think much of my own mother. Sounds hypocritical after the opening statement, doesn't it? And maybe it is. But then, I don't really care whose genitalia works. Just because you can fuck and give birth means very little to me. 'Mom' is the female that raises you, teaches you, protects and nutures you...and that might be someone very different from the woman who squeezed you out.
For instance, one of my friends will refer to 'Mother' when we talk, but I know that the person in question is his biological grandmother...she is the one that raised him. I know others who are in contact with both their mother and their step-mother...but for whatever reason, 'Mom' is the step-mother.
So, today, don't just pay lip service to the woman whose crotch you crawled out of. Tell the woman who helped make you who you are that you appreciate her efforts.