I just viewed the photo full-size. You may not like this, but here is what I see:
An Athearn SW7, worth maybe $20.
An Atlas/Roco SD24, again worth maybe $20.
An OLD AHM C Liner, worth maybe $5.
An old Bachmann (?) 4 wheel diesel switcher, again worth not much.
Several Model Power passenger cars, maybe $5 each.
A bunch of old Tyco and Bachmann and Model Power freight cars. Again, maybe $5 each.
A bunch of pre-made, low-end Plasticville buildings. New, they are maybe $20 or so each. Used, less.
A pair of $5 train set power packs.
A 4x6 piece of plywood.
Some plaster mountains.
There really isn't much there to entice anybody to want it. Maybe the best thing is to remove the stuff that isn't permanently attached, and put it either in the garage or basement, and bring it back out when you either have more room, time, and/or resources to devote to it.