I haven't the MSM name at hand, but it seems to be something like
methylsulfonylmethionine (correction welcomed), and in any case
methionine and cystine/cysteine are sulfur-containing amino acids in
virtually any food.  I've not heard of sulfur deficiencies.
   Wheat and barley grass are young, so any grass juiced young should
work. Lawns are older and fibrous. Alfalfa is most nutrient-packed
before bloom, early spring dandelions are a delicacy, as are those
grown for greens, and crabgrass seeds are quite nutritious-- but
mowing the grass isn't quite the same as growing it under controlled
conditions, outdoor or in.      Pet