The rattan mat is ideal for this. We didn't actually buy it for consumption, we thought it would be nice for them to have different textures to sit on and lie out on.
The rattan mats are an absolute hit. We were baffled when they started eating them but actually they really enjoy scrabbling around on it, gnawing at it, and when it's reduced in size a little they can grab the edge of it in their teeth and toss it around. It's a great boredom breaker for them.
We are on our second lot of rattan mats now, and expect to be buying them every few months to keep them entertained.