yeah as a fun side-note . . . this is a pretty great reason not to eat box turtles. depending on how large a part of their diet the mushrooms are, they can be quite toxic.
I have a personal theory about boxies as well . . . seems that at times their markings do a great job with camo, yet at other times they scream out of the background. this is (in my opinion) a devilishly clever evolved combination of both cryptic coloration AND aposematism.
that having been said . . . a question that might be worth asking is whether or not there's any correlation between gender and food preference (since males are almost universally more brightly colored than females). it would be neat to think that dimorphism in this species fits cleanly to support both aposematism AND sexual selection, but the answer seems too obvious and cookie-cut. there are a billion behavior-related factors to consider (nevermind the mess genetics would incite).
either way, its the kind of topic I find fun to chew on.
those mushrooms, however . . . not so much.