Try executing:
$Version
it should be 10.2 or higher.
You could also make it yourself with something like (10.1 and higher):
Polygon[AngleVector /@ Subdivide[0, 2 \[Pi], 7]]
or version 1 and higher:
Polygon[Table[{Cos[\[Theta]], Sin[\[Theta]]}, {\[Theta], 0, 2 \[Pi],2 \[Pi]/7}]]