Mushroom seeds are shimmered from jungle seeds. There is a drop well before moonlord for getting shimmer. A previously useless drop which I tweaked and renamed. Check recipe browser for a hint. There's a vanilla method adding in 1.4.4 for making a jungle. However, the mod adds a recipe for jungle seeds using the same items as the method to make it more clear.

Thanks,its just corruption seed and cleansing powder