A panorama of family diversity can be seen, and displayed, in the traveling photographic exhibits offered by the Family Diversity Project.
More resources for family diversity are provided in the UUA's Tapestry of Faith program for youth, Families. You can browse this curriculum online.
Consider a Buddhist meditation for Mother's/Father's Day or another occasion. Find a flower meditation on the Buddhanet website. Or, use the "pebble for your pocket meditation" from Planting Seeds by Thich Nhat Hanh. Each person holds four pebbles in a pocket and takes them out, one at a time, saying these words:
[1st pebble] I am fresh like a flower
[2nd pebble] I am solid like a mountain
[3rd pebble] I am still like a lake
[4th pebble] I am free like space around me and inside me.
Find Pebble Mediation cards that demonstrate the practice here.
The Origins and Meaning of Mother's Day
Read the UU World article by Donald E. Skinner, "Mother's Day for peace, as Julia Ward Howe intended; Kansas City Unitarian Universalists promote Mother's Day founder Julia Ward Howe's message of peace" (2008).
Read Rev. Dr. Wayne A. Robinson's May 8, 2011 sermon, "The Next to Perfect Mother's Day Sermon," on the website of All Faiths Unitarian Congregation (Unitarian Universalist), Fort Meyers, FL.