Lag bolt with attached coupling nut?!? - Garage Stirage

I want to build storage shelves around the top perimeter of my garage, inside. The shelves will be attached to the wall on one side and "hang" from the cieling on the outside edge. I want to use Hanger screws into the cieling rafters with a coupling nut. Threaded bar stock would pass through the bottom of plywood shelves (with washer/nut)and thread into the coupling nut that is also threaded to the hanger screw. This would support the outside edge of the shelf. The shelfs would be about 20" down from the flat cieling.
Here is my problem...
On a recent bike ride, I found lying on the road the following bolt - a lag bolt with a Hex Head that was threaded(1/4x20). This is a single bolt with a wood thread on one end and a hex head on the other that is threaded and will accept a 1/4x20 bolt. It combines both of the parts that I need (threaded hanger bolt + coupling nut). This seems to be a specialty part. It has no makings on it. I have been to all my local big box stores with it and they do not have it. Nor do they have any idea about what it is called or where to buy it.
Can you point me in the right direction... Where can I find this part? Have I found this one perfect fastener with no others for it to share in its purpose?
Please let me know that I am not insane but there is such a thing so I can rest peacefullly once more.