Can anyone help me identify these?  They were given to me by a friend who found them in a basement of a house he bought in Massachusetts.

how old a house?  They remind me of the cleats mounted on roofs to keep the snow and ice from avalanching onto the person standing at the front door.  But this is just a guess.

The side on the left looks concave; I wonder if they are supposed to go over the teeth of some kind of rake?

The house is 100 years old or so.  I will post a better photo.  

My first thought was tines for a plow because of the round notch on each one that looks like it would fit on a shaft.  But I couldn't picture how they would work beyond that.  Maybe they are really clumsily made shuriken.