There are hundreds of poems on the Internet that are dedicated to mothers and Mother's Day. So, all that you have to do is pick the one that best describes your feelings and emotions for your mother.
Even though it is easier to pick someone's lines and write them down for your mother, try to express your love for your mother in our own words. Remember, she is not looking for a great piece of poetry nor does she visualize you as a great poet. What is most vital to her is your love and appreciation. Let your love for her flow out spontaneously in a few lines of verse. A little poetic effort is the best Mother's Day gift she could have ever hoped for.