I'm not as purist as some people, but even so I would hesitate at that.
30 years ago it is possible they still had asbestos in them.
Even if not, they have:
Ceiling panels are composed of inorganic substances including MMVF22 [(slag wool) man made vitreous (silicate) fibres (CAS 65997-17-3)] and/or MMVF34 [(stone wool) RoxulÂ® 1000 (HT) mineral fibres], expanded perlite (CAS 93763-70-3), clay (kaolin, CAS 1332-58-7), and recycle paper (CAS 9004-34-6) using starch (CAS 9005-25-8) binder to form a solid dry matrix.
The vitreous silicate fibers is like fiberglass. It is irritating to the skin and bad for you to breathe.
In the meantime it is all inorganic and so does not benefit your soil at all. Your soil will benefit from organic mulch - grass clippings, fall leaves, wood chips, shredded paper, compost, etc.