An enigma. At least to you

Cursing, you rub your shin and glare at what you tripped over. It's a thick metal pipe about a foot in diameter with a mushroom cap, sticking about eighteen inches out of the ground. You curse it, and curse the vegetation that hid it, pulling up your pant leg to examine your scraped skin.

What the hell is this, and what is doing out here in the brush, you mutter to yourself as your rub your leg, trying to ease the pain. Obviously placed there for some other reason than tripping you, but what purpose it might have you have no idea. It's solidly set into the ground, and doesn't give an inch when you try to shake it.

Still grumbling you climb to your feet and start to walk, taking more care as you stride through the undergrowth. You haven't gone ten feet when you find another similar object. You stand puzzled, looking at it and trying to determine it's purpose, wondering why two such artifacts would have been embedded in the ground.

Shaking your head, you move on, emerging onto the lawn beside the first building you examined. Your knees are soiled from falling and your clothes need changing before you go to breakfast. For which you are very hungry, a growl in your stomach reminds you.