a thanksgiving card could be appropriate if you are thankful for his kindness he's shown you. if you write a thank-you statement inside the card, then it might not seem strange.

<font color=purple> Man can will nothing unless he has first understood that he must count no one but himself; that he is alone, abandoned on earth in the midst of his infinite responsibilities, without help, with no other aim than the one he sets himself, with no other destiny than the one he forges for himself on this earth. Jean-Paul Sartre </font color=purple>