Have you ever noticed that large urn behind 'Perry Mason' when he's sitting at his desk? I believe that urn contains the ashes of his dead mother. I'm thinking that his mother, although never seen on the series, died during the run of the show. Because the urn wasn't always there in the office. For awhile there wasn't even a place back there where he could have placed an urn.
Here's the evolution of his office redecoration:
I suppose it could have been the ashes of his father, but there's just something about Mason that makes me think he was closer to his mother. And it's nothing to do with the actor Raymond Burr, not that there's anything wrong with that. It's just that time and again Mason has shown a tender side towards his clients and others - even to the real murderers in some cases. And I think that's something he probably learned from his mother.....