Windsor Castle Park is located in downtown Smithfield with a slightly hidden entrance very close to Smithfield Station. The park isn't very large but has some cool characteristics with a pier over the water and of course their famous sunflower fields in July-August.
Besides having water access and a pier the park has a very interesting fenced wall to photograph at. The nice part about the park, it is totally free to the public unlike many of the parks around Hampton Roads.
For a very limited time during the heat of the summer, the park is full of sunflowers! Typically they are in full bloom in July to possibly August.