What is the plural of carved?

There is none because 'carved' is a verb, a Word for an action. The verb 'carved' is the past participle, past tense of the verb to carve. The past participle of the verb is also an adjective, for example a carved detail.

The noun forms for the verb to carve are carver (plural, carvers) and the gerund, carving (plural, carvings).