Billings
Two Moon Park “Two Moon Park (Yellowstone County) contains several narrow, gravel-surfaced trails that wind through stands of cottonwoods above and beside the storied Yellowstone River. The trails – Roche Jeune, Dull Knife, Mallard and Weeping Wall – can be linked together in various ways to come up with a number of do-it-yourself of loops and out-and-backs.” ….”At the Two Moon Park entrance you can jump onto the paved Dutcher Trail ,…. which from there winds down to the Yellowstone then upstream to Coulson Park.”
Swords Park Trail is 3.8 miles and described by the Rails-to-Trails Conservancy as wheelchair accessible.
Norm Schoenthal Island Trail 1.9 miles. Reviewers on AllTrails.com describe it as easy, and full of off-leash dogs and mosquitos. Best to go early in the morning.
Here is a website from Billings Parks and Recreation. It describes local trails by categories such as soft or hard surface. I suspect many of these trails would qualify for this website, but ease and accessibility are not directly addressed. Their telephone number is (406) 657-8371.