In the BBC show Casualty on saturday night one of the nurses stated that he had full sets of Spiderman series 1, 2 and 3 trading cards.

This is the first time i have ever heard anyone mention trading cards in a mainstream prime time drama show.

Anyone ever heard it in another one?

Only in the last Avengers movie, but that doesn't fall into your "mainstream prime time drama show" criteria.

There was an episode of Everybody Loves Raymond where his daughter traded a valuable Pokemon card for a common card and he tried to get it back.

The guys on the Big Bang Theory are always playing board and card games and there was the Wil Wheaton episode where they had a gaming card contest in the comicbook store.

They are mainstream, but not drama.

The first trading card reference I can remember was in Star Trek: The Next Generation. 'The Most Toys', the Season 3 episode where Data was kidnapped by an obsessive collector. Part of his unique collection was a Babe Ruth card kept in a special case which gave out a brief scent of bubble gum when you opened its door. Although it was sci-fi, I'm pretty sure it qualifies as a mainstream prime time drama show.

In married with Children, there was a reference to trading cards by Al Bundy, although I think it was sports cards rather than non sports.