identified

I think this is a military button with crossed cannons. There are some visible stars around the perimeter. The back is illegible. There is something I've never seen on the back...there is a small metal "clip" going through the loop. Any and all thoughts welcome. Some photos are focused on...

I know that a regular civil war knapsack goes for about $100 to $150. But, this knapsack is identified as to be from the 8th New Hampshire volunteers. I was wondering if anyone has any opinions on the value of a identified knapsack in this condition?