Twas the day before Mother's day and all through the land,
One of my sweetie's favorite pieces of jewelry is a mother's necklace.
It is a simple chain with a small ring with a birthstone, one for each of the kids. Many woman have either a ring or a necklace already.
If you sweetie already has a mother's ring or chain, consider giving her charms soldered together to represent your marriage. It was not overly expensive but it is meaningful and unique. My sweetheart wears hers all the time.
Its probably too late to order from Lifetime Mothers, a leading on-line retailer of mothers rings, bracelets, charm, and necklaces. but they still have some good ideas for another time.