What this coin looks like (obverse, reverse, mint mark location, special features, etc.): There were two major varieties of the 1917 Standing Liberty. The variety above is of Type 2 on both the front and back of the coin.
Obverse Varieties: The difference between the Type 1 vs Type 2 Obverse can be identified by viewing the breasts of the standing liberty portrait. Type 1 features bare-breasts which offended people of the time and forced a new Type 2 obverse to be designed. The new Type 2 obverse features liberty wearing chain mail instead. The difference and comparison of the obverse is depicted below in the example image:
Reverse Varieties: The difference between the Type 1 vs Type 2 Reverse can be identified by viewing the placement of the stars around the eagle. Type 1 features 7 stars on the left side and 6 stars on the left with none below the eagle. The newer Type 2 reverse features 5 stars on each side of the eagle and 3 stars below the eagle - making the eagle aligned higher up on the coin. The difference and comparison of the reverse is depicted below in the example image:
Coin value chart: Typical coin prices, values and worth in USD based on grade/condition