Yes, traditional Jewish caskets must:
Be made with no work done on the Sabbath (Saturday)
Only using natural, biodegradable materials (generally wood)
Minimal adornment, representing the equality of all people at death
A plain or polished exterior is acceptable
The casket may be decorated with a simple Star of David
Nothing in the casket except the body and perhaps some earth from Israel
Read more: The Aron: Jewish Burial Caskets & Where to Find Them