I always went for simple, generic, hope you have a wonderful day type messages - nothing sappy, sentimental, or anything that I thought would be or sound untrue. For a long time, I just didn't think it would be right to send those 'you are a wonderful mother', 'the best friend/example/support', etc ..... they didn't seem true. Wasn't my style to be so gushy anyway, nor my mom's style to send or to like stuff like that, either.
Now, my relationship with my mom is better, my mom has done kind things for me and my family over the years of my marriage, I see and appreciate the growth of character she has had over the years and I love the example of faithfulness and compassion she has shown in taking care of my dad so well in his incapacity; I do love my mom and respect her now in a way I did not before - she's earned that now. So, some cards that used to not be so true seem a little more true (but I still don't send those cards that talk about what a wonderful relationship we've always had or how you helped me so much growing up or blah blah - my feelings about my mom now and the NOW of our relationship are different, but I just am not going to put a rosy gloss on my childhood and our relationship that just wasn't there then .....)