Sat outside for a while. I’d weld them to each side of a 12 foot 4x4 3/8” thick square steel and bolt it to the floor of my garage to hold up the roof.
they look like the parts that bolt to a table jig to keep a part from moving while it is being welded or machined or whatever.
Those brackets are to nice to throw away. Could actually be vase holders for a fancy Cadillac. Heres my 1920 Cadillac cup holders. The long ones are for the rear seat p***engers due to the 36 inch legroom.
Oxygenated stopping blocks. Retention brackets for establishing the angle of a dangle. Under the shoulder boulder holders. They could actually be rumbleseat lid stops from an older big car. Any backstory like where,when, what car?