Sclerotia?

[Mok]

Has there been any more advancements in substrate selection with the intention of producing mexicana sclerotia than rye grass seed?

Any new strains for this purpose?

[GETERDN]

i have heard that one can use wild bird seed but  havent tried and i have even seen pics of Sclerotia forming on popcorn inside a qt jar .

[Cyano]

Some people claim they have higher yields with rye than with rye grass seed. (with Mexicana A). Rice also seems to work. May be even better than rye grass seed, because rye grass seed is said to dry up easily while rice does not.
About new strains: There is a new (actually not that new) strain of Psilocybe Atlantis. Atlantis also forms sclerotia.

[Jacko]

Brown rice, supplemented with a little flax seed and a little rye grass seed should do ya well.  Gotta have respiration as you're looking at about 3 months in a jar or bag before good yeilds are a sure thing.  A couple friends reported no luck with atlantis   , but their efforts were not repeated.