I went there last year. Right next to it is a redwood grove. Pretty cool. 

This is Washington's field bed at Mt. Vernon. Take the time to look at the construction in the detail photo's. I saw the link you got that pic from.   In October 1775, shortly after assuming command of the Continental Army, George Washington acquired "a Field Bedstead & Curtains, Mattresses, Blankets etc. etc." Designed for portability and durability, this bedstead's tapering posts, turned legs, and rails are ingeniously hinged so it can be folded into a compact bundle for easy transport. https://www.mountvernon.org/education/primary-source-collections/primary-source-collections/article/field-bedstead

I would guess the Army Corps of Engineers in this case is not the Army branch but rather the civilian origination that is in charge of inland waterways and flood control. I found this on the internet; Carbon Canyon Dam, located near Brea, California, is owned and operated by the U.S. Army Corps of Engineers, Los Angeles District (LAD). It's primarily for flood control in the Carbon Canyon Creek drainage basin and is part of a system that includes Brea and Fullerton Dams to protect the coastal plains of Orange County. Construction of the dam was completed in 1961.   

Looks like a good one to me.  Does it have a "silky" feel to the front?  The ones that I have are very distinctive in their feel and almost a floppy, silky feel to them.  Based on the pictures, I would say you have a good one here.

Of all the things I have never seen before I gotta say this is cool. My gut feeling based on almost nothing is that this is post Revolutionary war. The metal work on the bed frame hints at something later on in the industrial revolution. Just my two clad cents.  

Welcome to the forum. My maternal Grandfather grew up on the Isle of Wight.

I hope he’s still around, great guy.

That's it.  That was one of the details that drew me to it.

Thanks for the response.  Much appreciated.

No. The washers would not have the green verdigris on them had it been re-webbed. I dont see any evidence on the outside of rivets being removed. If it was put away for a long time there is no reason the webbing would be trashed. What brand liner is it? Inside the crown should have a stamping or raised stamping of who made it.