Best plants to grow for compost

[Snadger]

Buddleia. Larger prunings can be used as pea sticks or chopped up for the compost bin.

[veggiechicken]

I like to see the Buddleia in flower but, turn your back and its seeding everywhere. Its another plant I need to be more ruthless with. Sticks usually end up being chopped onto the path.

[Thelma Sanders]

Mustard Green (or Southern) Giant gets planted by the Nepalese families on our plots, eat the young leaves and compost all the older/bigger ones. It grows all year round and they swear it keeps down weeds as well
Sounds perfect to me - so I ordered some from Kings to try myself this year.

[ESBkevin]

In terms of bulk for the space used - sweetcorn. Reasonably fast growing and if you're composting it chop when full height without waiting on the cobs. You might get two growths if you have seedlings ready to go again.
For free from nearby hedgrows, nettles are rich in lots of essential nutrients and fairly bulky. They make excellent compost and are regarded as a natural accelerator in composting, don't worry if you accidently harvest other vegitation. Around June time they are fairly tall but have yet to get harder stems. A long handled sickle and a garden fork (plus long sleeves/trousers and gloves) are your friends.
Field beans are a cheap seed for green manure, they leave the nitrogen nodules in the soil when you chop them off and provide plenty of vegitation fairly quickly. I tend to mix them into other green manure patches.