plump, soft
He sank back into the soft cushions of the sofa.

couch (esp. AmE), sofa
scatter (BrE), throw (AmE)
seat

plump, plump up
She plumped up the sofa cushions before the guests arrived.

cover

on a/the cushion
I rested my elbow on a cushion.

Cushion is used with these nouns as the object:
blow, effect, fall, impact