I didn't build them or paint em. They just showed up in the floor. I would like to know the painter!!!?

Your Mrs.??

Very creative saw horses.   Drop a couple 2x4s in the slots to span between them.  That's my best guess. 

4D

Maybe used for a break down table for craft shows.  Two by fours and a plywood top.

I can tell none of you guys are quilters. We have 2 ten foot 2 x 2"  that go in the slots for when she ain't making stained glass thingies, she is making quilts.  If she starts some other hobby she won't have time to cook or do the cleaning of the house and running errands, running the weed eater, ridding the lawn mower or take care of my aliments. Its a good thing she is an RN for I sure would not want someone messing with me that didn't know nothing.

   smallpatch

It's great that you have a wife with that training. My Phyl was a primary school teacher. She's a great help when I have an arithmetic problem.  And, she helps me with reading the big words, too.