Where does the Olive Branch (KOLV) class D ceiling meet the Memphis (KMEM) class B floor?
The Class D airspace surrounding the Olive Branch airport extends upward to 2900 feet msl, excluding the Class B airspace.  So, your understanding is  correct. 

Here is the official description of this Class D airspace from FAA Order 7400.11,  Airspace Designations and Reporting Points: (emphasis is mine) 


  ASO MS D Olive Branch, MS
  Olive Branch Airport, MS
  (lat. 34º58'44"N., long. 89º47'13''W.)
  
  That airspace extending upward from the surface to and including 2,900 feet MSL within a
  4-mile radius of Olive Branch Airport; excluding that airspace within the Memphis Class B
  airspace area. This Class D airspace area is effective during the specific days and times established in advance by a Notice to Airmen. The effective days and times will thereafter be continuously published in the Airport/Facility Directory.
  
  AMENDMENTS 04/15/04 69 FR 5009 (Added)