zuma, My personal opinion is that if you didn't do the lawn, your W might think you're being mean. If it was me, I would do a really good job of it and not say a word or make it a deal at all. Just act as if it was nothing and not mention a word to her about it. Do it and then forget you even did it. Do it for your kids, not for her. Do it for you because it feels good to do acts of kindeness.
It must hurt that you were not able to celebrate your daughter's BD with her. Even though it's not ideal, maybe be grateful that she at least called to let you talk to your daughter. I have found gratitude to be a powerful way of attracting more good to me. Law of Attraction. -PH