Plymouth's Kellogg Park is the site of many seasonal events, especially, but not exclusively in the summertime -- Friday evening summertime stage concerts, Community band concerts, an annual Michigan Philharmonic concert, special summer events for kids, fall Scarecrow decorations, decorated Christmas trees, January's Ice Festival (ice carving competition), and more. If nothing else, sit down by the park's fountain and enjoy the afternoon. Of notable mention are adjacent activities -- Saturday morning Farmer's Market, the Penn Theater ($3.00 films!) and the many restaurants that border the park.
For an update on what's going on in the park, check a local website for a schedule of events.