Rocks with grains, like wood?

[Wishbone]

These were found in a creek in Southern BC, They all are smooth to the touch, with no sharp edges. I've learned that's from rolling down the creek or river. They are all shaped different, and are different colors. The thing they have in common is that they have grains? I made them wet so it's easier to see. Like a coffee table or something. What is this "graining" called please? And does it have any meaning to us miners?
Thank you.