Could someone help me identify these pins?

[demarjaso]

My grandpa had alot of military memorabilia. I found this massive collection of what looks to be black iron military pins. Could anyone help me identify them and tell me what they're for, what branch etc?

[der_adler1]

All are US Amry branch insignia.

Starting from the top:

Transportation Corps

Ordnance Corps

Signal Corps

Quartermaster Corps

Military Intelligence Corps (the photo is sideways)

Corps of Engineers