I bought out a box of tools. I found these 2 pieces together in a little box. No markings, i have no idea what they are for. I'm only assuming that they go together because they were stored together. The bigger piece is 5" long

Your pictures are too dark to tell what the top item is.  The bottom item is a toolmaker's knife-edge straight edge.  It is probably a Brown & Sharpe No. 530.  They came in lengths of 2 1/4, 3 1/4, 4 1/2 and 6 1/4 inches.

Thanks, looks like you are correct. Here's a better pic of the other piece as well

Looks like a boring bar holder.
For clamping a round bar in a square lathe tool holder.