We can only offer suggestions based on the photos. If you compare the information in each link with the tree in question you may begin to see subtle differences that will help you to identify the tree.
This article has information about the U. laevis but also says there is a variety
U. parvifolia in Serbia.
http://en.wikipedia.org/wiki/U...
Doing this quick research I learned that the samaras of some Elms are edible.
