Not anymore. The last uniform in which a commissioned officer wore rank on their collar was the Battle Dress Uniform/Desert Combat Uniform, which has since been replaced by the Army Combat Uniform, where the rank in worn on a flap on the front of the shirt.
An officer in the United States Army who wears a silver eagle is typically a Colonel, which is a rank above Lieutenant Colonel and below Brigadier General. The silver eagle is worn on their collar insignia denoting their rank.
Schultzstaffel commonly referred to as SS due to the Sig runes worn on the collar, but they were also identified by the sleeve eagle on their left arm instead of the breast eagle that was worn on the right chest by the Wehrmacht.
A cravat is worn inside a shirt collar.
be worn open
You didn't say what branch but usually the collar on Cammies same place as enlisted or towards the end of a shirt jacket epaulet same as on a dress uniform. There are uniform specs for each branch that say where exactly on collar insignia is to be worn. Like 3/4" back from front, 1/2" up from bottom, etc.
A full bird Colonel. A silver oak leaf would be a Light Colonel (Lieutenant Colonel). A gold oak leaf is a Major.
Blue Collar
Aegis
For PVT to SPC the gold rank is worn on the collar. For SGT and above the rank is worn on the shoulder boards.
The collar that is worn by the horse when pulling a load predates the ancient Egyptians, which would make it about 7000 years old.
A small bouquet which is worn on the lapel. (top right or left by the collar)
A full bird because of his eagle insigne.