If you bring the pine cones into the house, they should soon dry out and open, which gives the rabbit something to get hold of. Make sure they are not mouldy if they have been lying out all winter.
Apple tree prunings would be great, though shortlived, toys. The rabbits will nibble off all the bark and have a lovely time doing it. I sometimes tie flexible branches into a knot so the buns can fling them around.
I wouldn't use the trimmings from trees that have been sprayed... Not sure what chemicals might be in the sprays. Willow, poplar, elm, pear and sugar or silver maple are all fine for rabbits as well as apple.