I don't know much about post cards, but my thoughts are: (1) they have value, and obviously some more than others (2) blank is not necessarily better. The ones with stamps help to date the cards, and the content of the message may ADD to the value (wouldn't you love to have a postcard with a message from someone just before they departed on the Titanic? (3) things like this seem to realize more value if they are sold individually or in similar groups (foreign, U.S. etc.). (4) Usually, older is more valuable, but just like chips, not always.

I would not rush to sell them - there may be some decent value there. I am sure you could probably find a group like the "Chip Board" for postcards out there.

Sorry about your mom. I've been there.....