Thanks for writing. Both green grass clippings and alfalfa pellets are nitrogen sources --- so you'll need plenty of dry, fallen leaves, weed-free straw, or other ""brown,"" carbon-rich materials to balance it.
The general ratio is something like 6 to 8 parts brown, carbon-rich material to every one pound of green, nitrogen-rich material. If you have too much green material, your compost may start to rot and smell badly instead of decompose into rich compost.
---Justin, Senior Garden Editor, BHG.com