Per Cemetery records, Aaron Forrest is not interred at Elmwood Cemetery in Memphis. His body still lies at Odd Fellows Rest Cemetery in Aberdeen Mississippi. The headstone at Elmwood Cemetery is a cenotaph.

Married Sallie L. Dyche in Sunflower County Mississippi on July 30, 1862. She was the daughter of John T Dyche/Dycke and Sarah L. Prewitt Dycke.

Memphis Daily Appeal
April 26 1864
Colonel A. H. Forrest died at Aberdeen, Miss., on the 19th instant, and was buried from the residence of Kirk Brewitt, Esq., on the 21st, the funeral services being solemnized by bishop Paine.

The Daily Confederate, Raleigh NC
May 3 1864
Col. A.H. Forrest died at Aberdeen on the 19th or 20th inst., and was buried from the residence of Kirk Brewitt, Esq., on the 21st, the funeral services being solemnized by Bishop Paine.

Although newspapers reported him dying in Aberdeen Mississippi, I've seen other references to him dying of pneumonia in Dresden Tennessee. Another source, Official Records of the Union and Confederate Armies, 1861-1865, Series I page 374 has him dying in Jackson TN.

Headquarters of the Post,
Columbus, Ky., Friday, April 15 1864
Capt. J.H. Odlin,
Assistant Adjutant-General, Cairo Ill:
Captain: i have a scout just in from Jackson, Dresden, and that line, and I have every reason to believe his reports reliable. He was employed by General Smith and Colonel Waring. He reports as follows: General Forrest has two divisions--First Division, 3,400 strong, which is concentrated at Jackson, Tenn.: Second Division, 2,000 strong, concentrated at Dresden; 1,000 under Duckworth, from Jackson's command. Forrest said that a large force of our troops had landed at Pittsburg Landing, and that he was going to drive them back and across into North Alabama. The Second Division is said to be about to cross at the mouth of the Big Sandy into Middle Tennessee. My scout thinks their object is to get behind Chattanooga, somewhere about Winchester.

"Col. Aaron Forrest, Brother of the general, died at Jackson on Thursday night last."

Generals Fitzhugh (Stephen D.?) Lee and Jackson, with 9,000 men; are reported near Memphis. I shall try and rebuild the telegraph between us tomorrow. All the small squads are ordered to join their commands immediately at Dresden under General Buford, who is on his march there.
I am, captain, very respectfully, your obedient servant,
Wm. Hudson Lawrence
Colonel, Commanding Post

The Public Ledger (Memphis) reports on March 30 1868, the annual commemorative day held at Elmwood Cemetery would see "the remains of Gen. Preston Smith, Colonel Jeffrey Forrest and Colonel Aaron H. Forrest will be brought and interred on that day" at Elmwood. According to Elmwood records Jeffrey Forrest remains arrived at Elmwood on March 27, 1868. There is no mention of them receiving the remains of Aaron Forrest although there is a marker for him in the Forrest plot. On April 24 1868 the Public Ledger printed a detailed description of the funeral arrangements for General Preston Smith and Colonel Jeffrey Forrest.

Elmwood does not indicate where Jeffrey Forrest's remains were coming from but the 1939 Application for Headstone states that the stone was to be shipped to H.L. Baker, Aberdeen, Monroe, Mississippi and that interment was at the Odd Fellows Rest in Aberdeen. Aaron and Jeffrey were both interred at Odd Fellows Rest but when it was later decided to re-inter them in Memphis they could only find the remains of Jeffrey.