I don't consider seated dimes and quarters to be "artifacts", do you ?
I doubt that. It's actually VERY RARE that any places EVER dreamed up "permits" for md'ing, in the entire USA. Like in the state of CA, for example, I can think of 3 cities, and perhaps 2 counties , that ever dreamed this up (and it would only be for *just* those city or county parks. Not "all land", blah blah). And the dirty little secret is : You'd be hard-pressed to ever get carded, or find anyone who cares about it.
So I bet there's hardly any cities or county-park systems in TX that have dreamed up a "permit". And the LAST thing you want to do, is go asking "Is there a permit". Lest you be swatting hornet's nests, and find someone to interpret that as a "Can I metal detect" question. And pass out a whimsical "no" to the "pressing question".
If someone is concerned that a place "might have a permit", then they can look it up for themselves. Park rules, and available "permits" info (a revenue source for the entity) are going to be no secret in today's digital day & age. If you see nothing there that says "permit", and nothing that says "No md'ing", then presto : No permits and not disallowed.