Pearl is the appropriate theme for a 30th anniversary present, so pearl earrings for mom and cufflinks for dad are perfect gifts for traditional parents. Another traditional option is a mirror with pearls in the frame and the parents' wedding date etched in the glass.
A couple accumulates a lot of memories and presumably a lot of photographs during 30 years. A present sure to touch a parent's heart is a collection of special pictures in book form. Many online photo companies offer templates that make it easy to upload digital photos, add captions and create a journal that maps the couple's path from the early days to current times.
For parents who like to travel, an all-expense paid trip is a great way to show love and appreciation. The children in the family can plan and pay for the trip then surprise the parents on their anniversary. A re-creation of the parents' honeymoon or a trip to a more exotic location are both good choices.
A less expensive option is to plan a pearl-themed anniversary party. Dinner at a high-end seafood restaurant is a good opportunity to plant a pearl or two in an oyster for a fun surprise.