yep ! I'm serious when I say it's there to Mark the area.
Search it carefully, there may be a cache of some Type,
it may be a good Hunting Spot, Or simply litter that was Repurposed
of course, Party Spot even. But I'm guessing someone wanted to remember that Spot for some reason.
Could be a Dogs Burial Spot too But Doubtful if so far back.
Being how wide open it is, I'd detect every Where I can see it.
I'd Especially start where it is Looking from as far away as I can See it, & detect all the way up to the Tree first.
I'd take it down & Gut it Too, then put it back of Course.
type of finds detecting should tell you something, if allot of brass or can tabs.