Thrown in whole, cut up or cooked it will get eaten eventually. I normally food process all food going into the worm bins as it allows a better picture of water content and overall amount. Both cutting it up and cooking it will help the bacteria to break it down faster. This goes for all food items added to a bin, The choice is yours.

Rhubarb is probably alot like celery with a high water content, not as much as a melon but above average. Just something to keep in mind.

Bryan