Bunnies laying down to pancake are a great sign, it means they are comfortable.
Rabbits do need enrichment items (toys), but not all rabbits like the same toys. My former rabbit loved fling toys--things like baby toy keys that he could throw with his mouth. My current rabbit doesn't really like those; she prefers chew toys such as willow balls and loves running around her tunnel.
Here is a great resource on how to win over a shy rabbit if that is something you are still concerned about.