The Pebble from Generations

An old pebble, from an extinct beach,
Now high on a shelf, out of reach.
Passed down through generations, its so old,
The story about it, is yet to unfold.

Dirty, light, and small,
Has stayed as our family tree grew tall.
I'll never let it down,
And it has never made me frown.

Gave me lots of good luck,
And worth way more than a buck.
Forever it will stay,
And hopefully it will stay that way.