I try and read the person I'm asking. Some you can tell are willing to say OK right away with no stipulations. Others have that hesitation where you feel you need to add something to the pot to get an OK.
I agree with cherry picker. Each permission is different. I don’t even bring it up unless they say something about it. I was just at a permission where I told them they had first choice. The one I was at yesterday the owner didn’t care. I have a friend that wants what ever we find on his farm. And some just like to see what I find.
If they have an interest in the history I ask them if they'd like to see what I find. I'm only really interested in coins and will offer any relics I find. But I won't share my coins. If they want what I find, I'll go look somewhere else.
I'm currently trying to get a permission for a large lot in Charleston. I told the owner that I'm an amateur historian and that I'm trying to nail down the position of a colonial historical military thing (all of which is so) and I think I'll be getting the permission. Here's hoping! It will be fun and easy going if it works out. No strings attached so far.