I know this wasn't the intent of the thread, and I appreciate what the intent was; but my mother died on Mother's Day about five years ago, and I had totally escaped/forgotten that today was Mother's Day in the United States until I read this thread topic.
I guess due to all the COVID-19 news I somehow escaped the usual media barrage of Mothers' Day fanfare that is usually on the television/radio/net.
While I was never distant with my mother, and we had a friendly/healthy rapport, I still regret not being able to call her now. I called her when I should, and generally treated her well -- but not being able to call and talk to her any day, but most especially today, is still a regret.
Whenever a project goes well, or I unexpectedly did better at something, or something fantastic or terrible happens to me -- there's a moment still , internally, where I think to myself "I can't wait to tell her.", usually followed by sadness during the realization that my idea is fantasy, she's long gone and I had forgotten in that brief part of time.
So, I share your sentiment for those out there that shared the same kind of relationship with their mother that I got to experience -- call your mom. One day you won't have the option to do so, and it's tough once you're unable to fulfill that desire.