Collecting Stones in the wild in The Netherlands???

Hello all, I travel a great deal for my work and next week I am in The Netherlands with possibly Sunday 11/11/12, or evenings during the week, available for some personal time. Does anyone know of any areas in The Netherlands that has potential for collecting interesting stones? The Rijn River banks? The coastal area? Any ideas? Just a query if someone knows of a place. Thank you for sharing if you do!!! You can always PM me if you want only me to know your secret spots

Hello Dennis,
In the Netherlands stones have to be imported!
In our flat delta-land we have sand and clay.
We find, here and there, only stones that had been transported to here
in ancient times by glaciers from the north.
Sunip