It wouldn't hurt to feed them some of any of these. Biggest potential problem is choking on the larger turnips or beets and the fact that they will be about 80% water (silage is about 65%) so there won't be a lot of dry matter in them but they are digestible, contain some protein and energy and cows love them. $10 sounds check until you remember you're only getting about 400 lbs. of dry matter from a ton but still not prohibitive. You might have to sit on the tailgate with your pocket knife cutting them in half and hand feeding. ;-)
Later in the summer I usually have a lot of pears to get rid of. I take protein tubs of pears down to the cows. I take a machete and just chop them up while they're in the tub, then dump. If I see some large ones on the ground, I chop them before the cows get to them.
Ive been getting a few buckets of apples right now off the trees and I have about 4 or 5 that love them. I just cut slices off and toss them down. When the figs get ripe in a few weeks they will get down right nasty with each other to be the first one to get the sweet treats