Welcome, FeralMermaid! I must say that you are very well spoken. Perhaps an author? You tend to a very nice turn of phrase.
Yes, large trees do tend to accumulate things, since people like shade and sitting and lying about under trees was normal before the days of air conditioning. It does sound as though your tree was quite old, four feet across at the base could be easily 100 years old or more. If there has never been a home there though there may be nothing to find, unless cows in central Minnesota carry pocket change. You'll find the pages of T-Net littered with stories of "buried loot", most of which are just that-stories. Criminals tend to spend the loot, not normally being the types of folks who plan for the future. Still, stranger things have happened.
You did say something that tells me you've got the right attitude to be a successful detectorist, though. You mentioned research. That's the key to consistently finding nice things in this hobby, research and location. It's the dusty archives and old books, manuscripts and diaries that will put you on the road to finding the old stuff. After all, you need to go where people lose things to find them again.
If that's your photo in your profile, then you should have no problem getting permissions to dig places. A young lady will get permissions to hunt places us crabby old greybeards will be denied, in many cases, and that's a good thing for you.
As far as the beach goes, remember; people tend to live in their own little bubbles. They are there to do what they go to the beach for; swim, recreate themselves, have a few beers, whatever. Your metal detecting will get about zero interest, except possibly from kids; kids are curious. Adults tend to think of Detectorists as somewhat goofy, on the whole, and on the whole, we couldn't care less. As a self avowed "freak", I suspect you too will have a pretty low care factor about what other people think, so load up the old Bounty Hunter and head to the beach.
Enjoy the longhorn cattle!
