From NEMBA.org: Shawme Crowell is a 700 acre State Forest located in the town of Sandwich just over the Cape Cod Canal on the Cape. The park is best know for it's campground. There are almost 300 well maintained campsites. The Forest has about 5 miles of paved and dirt roads and about 10 miles of trails. The trails are very well maintained and trail markers abound. These trails are, as a rule, not very technical. There are a couple of steep climbs, but mostly the trails are rolling in nature, fast and a lot of fun to ride. Get a map at the Forest's Welcome Station and you won't get lost.
The best place to access the trails is at the back of the forest near the camper's dumping station. From there you will see one trail heading off into the woods, and another a short distance away across a clearing. I suggest starting with the one across the clearing. Expect to enjoy yourself here. A good rider could cover all of the Forest's trails in a couple of hours, but with one or two exceptions they are just as much fun in both directions.
There are a lot of deer in the forest, and the State has installed a tick killer / deer feed station, to limit them.