Wall Cemetery, its official name if such a thing exists in such a small, forgotten, isolated plot, is also called the Submarine Memorial. It's a tiny, private family cemetery that holds the remains of Rev. Allis (who was missionary to the Pawnee), his family and his descendants; Allis was a true pioneer of this area. The submarine memorial is a much later monument, and has an interesting and tragic story behind it and its reclamation. The cemetery is in need of help again, though. The WWII vets that were taking care of it can no longer mow and the cemetery is overgrown again during warm weather.
Wall Cemetery is located off the Bellevue exit on I-29, down from the Iowa Power Plant. When you take the Bellevue exit and turn east, or go across the Bellevue Bridge into Iowa going east, this funnels you onto a street called Bunge Avenue; you'll see the Bunge Corporation complex off to the north. Stay on Bunge Avenue going east for less than half a mile, and turn south (or right, if you're going east) onto the first road you come to. This will be 195th Street. Follow this about 3.3 miles. You'll pass Allis Street or Road, and in the vicinity of the first driveway after that you'll see a sign with "Wall Cemetery" on it; turn up the driveway and the cemetery is on your left. There is also an American flag flying over Wall Cemetery, which may make finding it easier. The aerial shot below shows the cemetery in relation to the Bellevue Bridge and I-29.