I am lucky enough to be able to visit Normandy annually [before COVID], as i am 7.5 hours away [3 hours driving, rest on the ferry] door to door from my house to the place i stay when there. I have not brought any sand back, but i did bring back some rusted bits of equipment which a local farmer gave me, one a rusted barrel, from front to just past the trigger guard, of an MG42, which i gave to a fellow collector for a milestone birthday.
I have below, it a brick from the outer wall of Hougoumont Farm, i was visiting and 2 guys were repairing the wall and i asked if i may take some that were not going to be reused, they said OK, I did make them both a cup of coffee and share a brew and a few M & S chocolate biscuits, as i had my camp stove with me in the car, which i think gained favour with them and in return i got three lead musket balls they had found when taking part of the wall down. I took a dozen bricks and gave them out to collector friends who collect Napoleonic toy soldiers, but kept a couple.