Bindi Irwin, Gigi Hadid, Gabrielle Union and more are taking to social media to celebrate the special day on Sunday with sweet social media posts. Irwin, who welcomed her baby girl Grace on March 25, shared a touching note on Instagram. «Celebrating my first Mother’s Day,» Irwin wrote alongside images that brought her and husband Chandler Powell's families together — including her late father, Steve Irwin. «This day embodies the extraordinary gift of family.