Of stegosaurus, of armored knight, of dinner table by candlelight. Remove my first letter, you'll find me tardy. All scrambled up I fall from wilted head. Both remove the first then scrambled: I'm that which is spun sans spool or thread.

Knick-knacks found in stores of thrift Souvenirs from time away Trinkets given as a gift Useless but to decorate

I’m small and dark, yet ground for bite, often beside my friend in white.

I hold secret words and valuable letters, but I am only secured by trust. I can also hold junk, but I'm not a trash bin. Sometimes large, sometimes small, sometimes flat, sometimes... less flat. Take away my last letter and you'll discover what I do to my contents.

Compound word The ultimate disguise for Superman.