Gardenia jasminoides 'Kleim's Hardy' (Cultivated- USA),Atlanta-P1290303.JPG?part=0.1&view=1&vt=ANaJVrET1aO1pdabWC0B1jxSpCFhw6O5wtFD6uufaw3IK6g4eB9xWSWYXBq7U5n3V0LjePsdE9uI2VWTTP4w4v0kxwrXA6Btw8cTNLJ79MMS67dcE_Yh170,Atlanta-P1290302.JPG?part=0.2&view=1&vt=ANaJVrFaYu6x2DKj_MHYi8dyVq4xjMuZff_i58Bjz-afqQ2B7cdLypDU5V4PgE3wiaxX_gmqIvWT6eUvHlyBFGxyKY-L01qprzegr5tEHtNR6uaN2cEOr1Y

Seen in the garden during my visit in October, 2018.
These were small shrubs, had seen them in other places too.
Gardenia jasminoides is planted in India
I do not know about Atlanta.
Side view of the flower is missing.

A similar plant I had seen in the Home Depot in Atlanta was Gardenia jasminoides 'Pinwheel'.
These were dwarf, compact plants.
I hope Gardenia thunbergia.
I guess … is correct !

Did you check for Gardenia jasminoides 'Pinwheel' that I had suggested?
Thanks a lot for the links.
Will go through them.
I went through the links. 
Your suggested id seems correct to me.