First of all skoivu, when someone says "such & such place has never been hunted before", that doesn't necessarily bear true. EVEN when it's the property owner himself telling you that. There's just too many scenarios (even if the property owner insists they would "certainly know", where this may not be the case). For example, I've been at stage stop locations I've researched out, 20 yrs. ago, via a ranch-hand, or some kin-folk who said "I don't see why not, help yourself", etc... Then 10 yrs. later, I decide to take some more stabs at it, and show up at the door again, and this time it's the wife, or son-in-law, or new owner of the house, or whatever, answering the door. They might say "go ahead, help yourself. No one's ever hit it before". And inside, I'm chuckling, because I know that I myself hit it 10 yrs. prior, when someone else had answered the door, or a ranch-hand leaving the gate winked at me and said "go ahead, but just shut the gate on your way out", or however I might have gotten in before. Then flash forward to the present, and I show up again, and again, whomever is saying "sure", says ".... and it's never been hunted before". This has actuually happened to me before, at several places! And what humorous, is the current owner (or person answering the door or whatever) just "assumes" that they'd have been privy to the info, if their wife, brother, son, or laborer had said "yes" to anyone 10 or 20 yrs. earlier. Or quite frankly, if the place (school or stage stop, or whatever) is out in the boonies, persons might have just helped themselves at some time in the years past.
So there's many reasons why your permission granter person may simply not know any better, and that it was hunted by persons who left you the nails, d/t they disc'd out the iron.
And a word about 1-room school houses. If your site truly was "virgin", it does seem odd that after 100 yrs. of use, that there wasn't any coins there. When did it cease operation? Because if it was before ........ say ....... 1940, then it may be true, that there wasn't any coin losses there. Did you get other indicators like buttons, suspender clips, pencil eraser tops, etc....?
I have researched out one-room school house sites here in CA that we KNEW for a fact they were virgin, because the source info we used to sleuth them out, was only just then released in a history book. And once there, found indications that we were the first ones. You know, like brass doohickeys, suspender clips, overall buttons, etc... And what was odd is, that if the school were abandoned and gone before 1920 or so, we found that they RARELY ever had coins at them. Even ones that had a documented 20 or so years of usage (1880 to 1900, or 1890 to 1915, etc...). Because you see, oft-times those schools had as little as only a dozen or 15 students (typically just 2 or 3 families in the area, sending 3 or 4 kids each). And back in the day in country life in the 1800s, there was absolutely no need for kids to carry or have money. There was no school lunch programs, etc... in those days. So unless the school doubled for use as something else where adults would have used it too (grange hall, church, dance-hall, etc..), then it's entirely possible that the kids who were there, simply had nothing to loose. This all changed in the '30s and '40s though:
The same demographics can be seen at school yards in the inner city too: If you talk to old-timers who were the first to hit some inner-city-urban school yards, back in the old days (mid 1970s and earlier), they will tell you that even then, the vast majority of the silver we were finding, was '40s losses and later (ie.: mercs, roosies, washingtons, worn SLQ's, etc...) Even though we might be hunting elementary school yards built in the early 1920s, we didn't get any barbers, or early crisp '20s loss silver coins, it seemed. At first, we'd think "it's because we're not getting deep enough". But flash forward to the days & age when depth was no longer an issue, and we reached deep enough that those occasional crisp green '10s wheaties, or the crisp low-circulation '20s mercs were within our depth range, yet the #'s of silver coins and IH's, etc... never compared to the volume of silver coins that came out of those SAME schools, which were clearly '40s/50s losses.
The reason is, that starting in the post WWII times, prosperity was much changed. Kids started to have a few coins in their pocket. School lunch programs came into being, so kids had reason now to bring their coins to school. So there may be some truth to what 90+ yr. old folk will tell you, that when they were kids, they didn't have 2 nickels to rub together. But heck, when I was a kid in the 1960s, we always had coins, for some reason, in our pockets.
