Where would be a good place to treasure hunt with a metal detector in or around Breda, Netherlands?

I have a metal detector and I am looking to find some interesting relics. I would like to donate anything I find to museums

Don’t.

You will disturb all historical information.
The surrounding information is more important than the artifact itself.
The only place you can use a detector in the Netherlands without ruining things is the beach.

Diggin History #1 – Metal detecting an old Boy Scout camp in Chicago