As far as I know, the command findAt(...), which would be used to find an edge, a face etc. at a specific location, can not be applied to mesh-elements. However, you can use slightly more complex commands like

getByBoundingBox(...) or getByBoundingCylinder(...) (accessed via mdb.models[name].parts[name].elements or mdb.models[name].rootAssembly.elements)

On the example of Bounding Box, you would define coordinates for two different points (x,y,z) which then describe a Box and Abaqus would find all mesh faces within that Box. If you know, how big your mesh elements are, you also know how big your bounding box should be, to find the mesh-element with your x,y,z, coordinates in it and read the stress values.

Having said all that, it is clear, that, unless your x,y,z lies by chance on the integration point of the mesh-element, the stress value will not be the exact stress value for your coordinates. Achieving this should be slightly more difficult.

Thanks Oliver.

I figured out two other solutions, thought would share :

1) create a path using the points using

session.Path(name='Path-1', type=POINT_LIST, expression=(points))

points is the list containing all the points

and extract data

2) Using a matlab code

find the element in which the point lies, for a linear element , stress value is constant. so take the stress value at the integration point of the element.

You can always export your results and by knowing the element number you can easily Identify the element in question, although this method can be very hard for large models if you do not have the mesh map.