For your situation, I would try this.
Try to spot the coyotes before you try calling them in. Getting them to come into bow range will be extremely difficult with the terrain you are describing. If you spot one, or if you can't spot one but have a good idea on the direction they will be coming from, try this set up. Designate one person to be the caller and one the shooter. Since you have already spooked them they will almost certainly be more cautious and will try to circle downwind of you. Have the shooter about 30 yards to the downwind side of the caller, if you have a very slight breeze. If you have anything stronger than a breeze try to stretch this distance to about 50 yards. When the coyote has commited to coming close to the caller, stop calling. You want the coyote to be searching for you, not barreling in to eat. If they check up, give them some coaxing with a lip squeek or the little coaxer calls you can buy. When the coyote is in bow range, don't try to draw unless their attention is diverted from you. Once at full draw and ready to shoot, the caller can give a bark or whistle to get the coyote to stop for the shooter. If you have access to a decoy set that 20 yards upwind of the shooter.
If you have a decoy and remote caller you can set those 30 yards upwind of you and sit together and wait.
That is how I would approach it. Stick with simple distress calls: bird, rabbit, rodent.
Good luck and have fun.
Edit: I think they are eating corn and mice. Don't worry about matching their food source with a certain type of call.
