Small rocks in your gutters?
They are from your shingle roof and are pressed into the hot asphalt.
They protect you and your from the UV rays and make it fire resistant.
It is common for them to come off and get washed to your gutters.
They can turn into mud-like substance when wet and might clog your gutters.
When they reach the point where it looks like there is gravel in your gutters or downspouts your roof might be nearing the end.
They can turn into mud-like substance when wet and might cause your gutters to get clogged.
You should call a professional gutter cleaner!