So what is a momento? Something you can hold onto, something to remember an event by or someone with. When you hold the item, close and dear to your heart, you can remember the joy you felt.
I found it interesting to invert the nature of the word, and describe something totally different; something not nice at all. Each of the items described in the poem is a memory, but it is more tangible than that, they are diary entries allowing anyone who reads to relive the time.
For those who lived through this, with this, it is something more. It is the scars left on your psyche. Scars that itch and burn and never heal. Scars that remain and remind you of the torment. These are the momentos that some offer to their children, that husbands offer to their wives, that wives offer to their husbands. These are the momentos that were offered to me for years at a time, and I work very hard to forget.