A sign of a St. John's Wort flower is
that it has like a star burst in the middle of the flower center.. not a short one either,
they go out at least to the outter part of the flower..
The one picture/flower you posted,
has short stamens' in the middle..
not bursting out...
Here's a picture of a St. John's Wort..
click This next one looks to me to be a Wild St. John's Wort, it's dark/orangish, rusty colored sorta...
click here