There isn't a specific Psalm that is designated for Mother's Day, but there are several Psalms that could be relevant to the occasion. Here are a few examples:
Psalm 139:13-14 - "For you created my inmost being; you knit me together in my mother’s womb. I praise you because I am fearfully and wonderfully made; your works are wonderful, I know that full well." This Psalm speaks of the wonder of God's creation and the special bond between a mother and child.
Psalm 127:3-5 - "Children are a heritage from the Lord, offspring a reward from him. Like arrows in the hands of a warrior are children born in one’s youth. Blessed is the man whose quiver is full of them." This Psalm acknowledges the blessings of motherhood and the importance of children in a family.
Psalm 113:9 - "He settles the childless woman in her home as a happy mother of children. Praise the Lord." This Psalm speaks of God's provision and care for those who desire to be mothers.
These Psalms (and others) can be used to reflect on the special relationship between mothers and children, and to give thanks for the many blessings that come with motherhood.