Kulikovo pole (Kulikovo field, from the russian work kulik, meaning snipe) is a historical area of famous 1380 Kulikovo battle against mongol inviders, situated in the south-east part of Tula Oblast.
Nearest train stations:
To get to location from those stations you'll need to change to buses, taxi or hitchhike (see sections below). Important notice about Ranenburg and Kulikovo Pole stations - most probably, if you're going to take this route to see splendid scenery, you're going to have following route in mind: a train arriving to Ranenburg very early in the morning (about 4-5am), bus to Lev Tolstoy (Chaplygin-Dankov), then change to local train to Kulikovo Pole (several times a week). There's no convinient train connection from Ranenburg to Lev Tolstoy and further to Kulikovo Pole unless you're going to stay overnight alone the road.
The only direct buses that reach Kulikovo Pole, are: Kimovsk-Monastyrschina (twice a day) and Kimovsk-Kurkino (twice a week, but catches both important landmarks). Most probably you'll want not to be connected to timetable of those buses, in which cases you can use more frequent buses that reach Kimovsk, Epifan' or Kurkino, and get taxi or hitchhike from there.
Turn from M4 to R-142 near Bogoroditsk and then to R-142 at Kresty - this would be preferrable route, avoiding Novomoskovsk industrial area with a bit busy roads. In case you're going from north-east, you may want to go through Mihailov on M6 then with R-132 to Gremyachee and R-114 to Kimovsk - all other roads contain either really bad quality stretches or in some cases (unexisting "road" from Gorlovo to Kimovsk) even non-crossable railroad crossings which will make you to just turn back. Notable exception might be the Dankov-Zhohovo-Kulikovo memorial road, which is farely passable *in good weather*, when it is possible to take field road, parallel to actually broken asphalt stretch near Zhohovo - just look, which way the cars are taking, there are enough there. Not advisable in bad weather though.
Main landmarks are connected by R-145 Kimovsk - Epifan' - Monastyrshina - Kresty highway, and R-142 Kresty - Kurkino highway, that are easily hitchhikable in day time, providing also last leg from bus or local trains. Other hitchhikible routes are R142 Bogoroditsk - Tovarkovo - Kresty, Bogoroditsk - Epifan' road and Dankov - Zhohovo - Kulikovo memorial road. If you're going to Kulikovo Pole through Kimovsk, you may want first reach Kimovsk with whatever transport (lots of buses), as it is a bit more complicated to hitchhike in a somewhat industrial area.
In addition to usual precautions take care about where you're going to stay overnight and what you're going to eat, as the place is rather remote, and it is a bit difficult to make a trip there from Moscow within a day. Unless you have a car or camping environment, take an excursion or have a reservation in the inn in Monastyrschina, you may find that there are no places to stay overnight in significant vicinity (closest will need you to get back to Kimovsk, Epifan' or Bogoroditsk), and the only shop and dining places close early.