Maple blocks

They look like they may be part of an old bowling alley,if that’s the case they may be full of nails.

Jim
I don’t know what these were used for. So far I have not found any evidence of nails or anything else. They all have two 1/2 inch threaded rods that go across the 15 inch width. It seems they were made special for whatever they were used for.
They clean up real nice.

Picture frame with light in the holes.

I’ll bet these puppies weigh 40 pounds. They would make a cool workbench top, but I can see you already have one of those in your picture. Consider a table… Top would be 4 of the longest pieces making a 60" length and the depth would be say 27" or whatever they trimmed down to for a common dimension. Legs on either end would be 2 blocks on edge to give a 34" table height. It would be a 250# table on which you could display a Volkswagen.