Maybe check newspapers online for the day each was born, and if allowable print off interesting things that happened that day, warm, happy, fuzzy articles, popular recipes from that time, advertisments showing prices and items from that time, homes for sale & their prices, anything you feel they would enjoy. Lots of fun stuff there!
You could also do the same
for the day they married. Make sure you print off the name of the newspapers and date on them.
Make a scrapbook from all the little things you find from the days of their births, marriage, maybe the day each of their children were born. Newspaper articles for Christmas for days that would have been special to them
A totally unique gift that can bring beautiful memories and smiles!