I worked in the yard for about four hours yesterday.  It felt great.  The sunshine was wonderful after all the rain we have had recently.  When I was just about ready to call it a day these beauties came fluttering through the yard.  One would follow the other and never strayed more than a few inches apart.  They seemed to like the bright pink lantana more than the purple butterfly bush that can barely be seen in the second photo.  From what I could gather , these are:

Giant Swallowtail (Papilio cresphontes)