You can use fresh wet buds and trimmings - even stems to make cannabutter with. Just add water to the pot enough to cover everything, then add the butter or margerine. Simmer - not boil - for 1 hour or more... When it's ready squeeze the plant material to get the butter back out and put the liquid in the fridge so it will cool and seperate. The butter will congeal into a hard green disk on the top and the dirty water and remaining junk will all be still left in the bowl.
The longer it's simmered in the water, the less green or "grassy" taste the final product will have.
Cooking the trimmings is a great way to dispose of the "evidence" from a grow.. looks and smells like cooked spinach when it's all done.
Peace
MC