Looking for rocky beaches for my autistic son to quietly sit and toss rocks into the water

Our current favorite is Mukilteo ferry dock. He can, will, and does sit for hours in one place and do nothing else. It’s calming therapy for him, gets us all outside together as a family with a picnic, games, etc.

We’re looking for new places with endless supplies of rocks, preferably fresh water lakes and rivers to avoid tide movements and smells. Our other favorite is cedar river between Renton and Maple Valley, and Keechelus Lake at Snoqualmie Pass.

Very interested in others if you have suggestions.

Thanks!