I like to think I wouldn't be quite that obvious...
OK, I admit it sounds very much like the Ring, more than I actually realized before posting it; but the Ring is only an almost-match, not a perfect one (e.g. what would 'keep the guard' mean in its case? And none of the places where it lay 'hidden' for a while was really its 'home'). Keep guessing!
(P.S. What warning? I was merely asking you to give me a few days time to think of a new riddle, and thanks for the waiting. You're welcome to guess, of course!
)