Most of the time sending a gift to a reporter is a bad idea. Journalists don’t take gifts. All news organizations have ethics policies about accepting gifts. Some won’t even let their reporters drink a free soda or cup of coffee, if it is offered by a source or a potential source (which means just about anyone).
Professional reporters and producers are trained to avoid conflict of interest or the appearance of being influenced or biased. While it is not likely a low cost trinket like a T-shirt or mug would sway a reporter to slant a story, it still could look that way.
In my experience, radio and TV people are generally okay with food. If you send a tin of cookies, a can of popcorn or a box of chocolates to the newsroom, the whole crew gets to enjoy it and talk about who it’s from and why. Items sent to an individual could be a problem, no matter how well-intentioned.
If you want to make a gesture of thanks, don’t make it an ethical trap. Send a simple thank you note with a few more good story ideas. That’s thanks enough.