Not a ritual, but the summer after DS had weaned, we saw these sweet little clay statues at the Three Rivers Arts Festival. Some were of families of varying types, dads reading to children, a mom nursing baby, slightly older baby at that..... DH bought me one of a mom nursing older baby. That commemorated DS's time at breast.
Now that DD is approaching weaning, much more verbally than her brother did--in fact she announced last night that she is going to keep nursing until she's 10
--I have gotten myself the nursing mom pendant from over at attachmentscatalog.com. When my first one got broken, I bought 2 so I'll have spare in case of another accident.