Found a cable in my backyard of a new house after raking the leaves. It is above ground for about 3 feet over some tree roots. It appears to be coaxial, but there are no markings on the jacket. The cables for my tv/internet service do not look like this, they are flat coming into the house. Any idea what this might be from? It looks like it runs to my neighbors backyard that is behind my house.
We won't be able to tell what it is from here. Call 811 (or your local/state one-call service if 811 isn't available to you) and see if they mark it. Better yet, see if you can meet/talk with the utility locating crew when they arrive; they may be able to provide you with more details than just a locate.
If it's abandoned according to them -- you should be able to just rip it out. If it's still active according to them, fetch your deed from the assessor's office and check it for rights of way. If it's active and not in a right of way, you have a case of trespass and perhaps other things as well. If there is a right of way, call whoever's on that right-of-way document and tell them to fix their cable so it's actually buried properly and not subject to mechanical damage.