Yes — rose petals (and rose hips) are safe and make beautiful edible foraging material, as long as they're free of pesticides.
Keeper's noteNever use florist roses (heavily treated). Petals from your own unsprayed garden, washed, are safe and gorgeous foraging. Dried food-grade rose petals and rose hips work too.
Why rose petals is good for parrots
Rose petals are non-toxic and a popular edible flower for parrots, and rose hips are a well-known vitamin-C source used in bird treats. The critical caveat is chemicals: florist and garden roses are frequently sprayed, so only use organically grown or known-clean petals.
How to serve it
Only organic/unsprayed petals — never florist roses.
Wash fresh petals; offer for foraging and shredding.
Dried food-grade petals and rose hips are safe too.