It's a key card, perhaps for a hotel room, more or less conforming to ISO/IEC 7810 ID-1, which is the international standard size for credit cards and the like.  The image is from Burningwell.org, which you should check out if you haven't already.  It's nothing but public domain stock and texture photos donated by the public.

The front has an autumn leaf on a black field, and the back has the black magnetic strip on a white field.  The image can very easily be swapped out for others, so potentially making a lot of different keys, credit cards, ID cards, library cards, etc.