Here's the Confederate Order of battle for Tom's Brook courtesy of the Eric Wittenberg North & South Magazine article I cited (source for him was the OR):
Lomax's Division
Imboden's Brigade (Col. Geo. Smith)
18th VA Cav
23rd VA Cav
62 VA Mtd. Inf.
Bradley Johnson's Brigade
8th VA Cav
21st VA Cav
22nd VA Cav
34th VA Cav Btn (detached)
36th VA Cav Btn
Jacksons' Brigade (BG Henry Davidson)
2nd MD Cav
19th VA Cav
20th VA Cav
46th VA Cav Btn
47th VA Cav Btn
Rosser's Division
Wickham's Brigade
1st VA Cav
2nd VA Cav
3rd VA Cav
4th VA Cav
Payne's Brigade
5th VA Cav
6th VA Cav
15th VA Cav
Rosser's Brigade (Col. Richard Dulany/Col. Oliver Funston)
7th VA Cav
11th VA Cav
12th VA Cav
35th VA Cav Btn.
Each division also had a horse artillery battery attached.
From what I read of the Union OR reports and Eric's article it was Johnson's Brigade of Lomax's Division that got hammered and that is the brigade from which the flag was taken as they faced Lowell's Reserve Brigade directly along the Valley Turnpike. If the MOH was awarded for the "32nd VA Cav Btn" flag and we know the 34th VA Cav Btn was on detached service it came, there fore, either from the 22nd VA Cav or the 36th VA Cav Btn. With the designation for the capture stated "battalion" I still lean towards it being the flag of the 36th.
Greg Biggs