Mothering Sunday is one of those Sundays which has the potential for great blessing, but also enormous complications.
There is always the worry about what we do with those members of our congregation whose mothers are/were not nurturing and loving.
For women clergy, especially those who are mothers, there is often a slight embarrassment, a feeling that the service is an exercise in self-congratulation – who am I, a mother, to talk about how wonderful mothers are?
One solution to both is to broaden the perspective of the service: to talk about, not only God our Mother (the true nurturer, the model of love), but also all those who have played a maternal role – both men and women. There is, of course, also the perspective of Mother Church and the family of the children of God. The introduction to this service for Mothering Sunday is a good case in point, and similarly this liturgy-for-mothering-sunday (somewhat different in style).
I hope some of the following helps as you’re putting together the order of service:
The RSCM provide this list of hymns and music.
Those of a Marian persuasion might find useful the propers from CW: Festivals for the Virgin Mary.