Can someone tell me what these are?

here's a little "Bumper Jack 101":

the first pic shows a flat support jack. that style of jack was used from the 30's through the early 1950's with older cars with "flat" bumpers and bumpers attached with exposed bumper support braces.

the second style bumper came around in the late 1950's and was seen as safer than the first style because the "lip" on the end of the support would catch under the bumper holding the jack in place. this style was used from the late 50's through the early 1970's. some cars with this jack also have small square "cut-outs" on the bottom edge of the bumper allowing the lip to fit into the cut out.

the third style jack came around in the mid-1970's and was seen as an even improved safety design. this jack fit into a slot cut in the bumper thereby making it impossible for the jack to slip out of the bumper. a lot of foreign cars also use some kind of jack that fits into a slot or rectangular or round hole.

bumper jacks are not as common today because of "run flat" tires.