import arcpy

contours = r'C:TEMPContours.shp'
con2 = r'C:TEMPContours2.shp'
d = {'a': 1, 'b': 2}
_list = [1,2,3]
string = 'test'

lyr1 = arcpy.MakeFeatureLayer_management(contours, 'contours1').getOutput(0)
lyr2 = arcpy.MakeFeatureLayer_management(con2, 'contours2').getOutput(0)
layers = [globals()[v] for v in dir() if isinstance(globals()[v], arcpy.mapping.Layer)]

print layers

for lyr in layers:
    print lyr.dataSource


[<map layer u'contours1'>, <map layer u'contours2'>]
C:TEMPContours.shp
C:TEMPContours2.shp