She is not mentioned in Zachariah’s will of 1832.

The progenitors of the Lamar family in Milledgeville, Georgia were the brothers John and Zachariah, who moved from Warren County, Georgia in 1810 and settled on the Putnam side of Little River, ten miles north of Milledgeville. 324 John Lamar lived in Putnam County, Georgia where he established what was to become known as the "old Lamar homestead." With him lived his bachelor brother, Lt. Col. Zachariah Lamar, a self-taught man who, like many of the men of old plantation times, devoted himself entirely to the world of literature and history. So when sons were born to John Lamar this bookish enthusiast claimed the privilege of naming his infant nephews after his favorite character of the moment and the parents evidently consented. So we have Lucius Quintus Cincinnatus, Thomas Randolph, Mirabeau Buonaparte, Jefferson Jackson, and a grandson Lavoisier Legrand. Zachariah later married, and his daughter, Mary Ann married Howell Cobb. Zachariah was a very wealthy plantation owner and left extensive lands and monies to his three children in his will of 1832. His wife was not mentioned in the will and presumeably deceased.

He is in Franklin County on the Reconstructed Census of 1790 for Georgia.
He was a tax payer in Baldwin County, Georgia in 1810. 624
He paid taxes in Captain Little’s District of Baldwin County, Georgia in 1813. 624
On the 1830 US Census of Baldwin County, Georgia, Z. Lamar is 20-30 years old and lives with another 20-30 year old male. He had no wife or children in 1830. M19 R16 P43

Baldwin County, Georgia Will Abstracts ZACHARIAH LAMAR 1/23/1832 - 11/1/18-- Wife: not named Children: John Basil Lamar, Andrew Jackson Lamar, Mary Ann Lamar Others mentioned: Lucius Q.C. Lamar; Jesse Robinson; Robert McComb; William G. Lane; Isaac Newell
Jesse Robertson was the Executor of the 23 January 1832 Will of Zachariah Lamar. The inventory and appraisement were on 12 November 1834.

Alternate Trustees mentioned in the will of Zachariah Lamar were Jefferson J. Lamar of Jones County, Georgia, and William Robinson of West Florida.

There are two children named Zachariah Lamar and a nineteen year old Horace Carnot Lamar 1804-1823 in Section I, Lot 8 in Memory Hill Cemetery in Milledgeville, having died in 1814 and 1826. Zachariah is also in Lot 8. If these are his children and his wife died between 1826 and 1832, she is not in Memory Hill, as no one fits. Was her name Robinson/Robertson....both in will as Trustees and witnesses. Jesse Robertson is called a Relation in the Will. Also note that the Will names both Jesse Robinson and Jesse Robertson...they are clearly spelled that way in the will.
Also
Louisa Catherine Jane Lamar ca 1804-1804 is in Lot 8-3
Thomas Robinson ca 1807-1811 in 8-4
Walter Lamar ca 1814-1815 in 8-7
William Lamar ca 1811-1811 in 8-5