some places are legal some are not. usually private cg do not allow one or the other, if they allow foraging, you better catch it as it falls as there is not usually there. You can bring wood if it is from that area and not transferred through specified lines defined by the state. I've never been to a state campground where you could not get wood as it is plentiful. I usually bring some and find some kindling or pick some up for sale, support the community, outside the campgrounds for a much better price. Some simply just require you to buy theirs, some for revenue some for peace of mind to satisfy laws, some do both.