These boards are Swedish bread paddles. 
The edges are very thin as they would have been used to slide under the loaf in the oven to lift it out. Much like modern pizza paddles. 
Fabulous as part of a collection or displayed individually. Great serving boards! 
This one has a really great little metal mend on the bottom to make its life a longer one! In the true vintage make do and mend way. 
Measurements: 33 x 49cm high