Mystery thing in my tire

Yikes!

That looks like the knob on my lawnmower that I use to adjust the handle height. It's clearly a hand knob for something.

Just put together some lounge chairs and had to screw the feet of each leg into the chairs. This looks pretty much the same. They were a three sided hard rubber/plastic foot moulded on a long threaded bolt. Could be something like that or @Lunatic59 suggestion. In any case not a good result for your tire...

Yeah, thankfully the tire shop patched it, so good to go. I was shocked how thick the stem was. I was expecting it to be thinner and pointy.

That is quite something to have pickup Betha. Good job the tyre shop could repair it okay. In Britain they no longer allow the use of inside tyre patches (Tubeless Tyres) but can use tyre plugs for the like of nail etc., if the damage is not too near the side wall area and within the central repair area section of the tyre.