When digging on someones place, I try to work that out specifically. I try to initially find something that they know they have lost. Sockets/tools around the garage anything that they have a vague idea of where to maybe look for a lost ring of keys or s piece of jewelry. If i can find that, then they usually will let me keep looking and keep what i find. They are already satisfied.
If its just a cold call, stop and knock, and nothing is sorted out, I will discretely mark or note the locations of targets and maybe dig just one or two of the best ones, and see whats coming out of the ground...take a break and show them what you are finding...if they have that gold fever Gholum "Precious Mine" glare in their eyes I just offer up the few I dug and go on my way....I am not digging shit up to give away. I tell them there could be more and work out a split 50/50, or if they want everything, then I will scan their property ( average sized yard) for a flat rate of $25- $30 bucks... I have had three people pay me to scan their yard once i approached them,,, Its rare, and even when the owners don't care what you find or keep, I always give them something especially if it is something that has little intrinsic value, and is more of a relic of the past or a lost memento... But I sort all of that out BEFORE i dig up the goodies.