Some of these are quite small studies, acrylic or gouache on 4x6 inch watercolour postcards.
A lady in one of the art groups to which I belong has a father living in Kissimmee, Florida. He is quite elderly and lives alone. He used to be an artist but can no longer see well enough to paint. She asked if people would be willing to send him cards with their art on them. For the price of a stamp every few weeks, it's more than worth doing.