Another something

[Vnaz50]

What I know about the things that I’ve found in my yard so far. 
Chert

Limestone

Dolomitic limestone

Karst pieces 

Oyters 

Clam

Shells

What would cause this rock piece to be black? It’s kind of like a piece of charcoal that had soaked and dried. 

[Vnaz50]

I’ve also found big tooth aspen leaves. Which until two weeks ago wouldn’t have been able to survive in our south Texas climate. And this cloth.