What is the best solution for allergic reactions for the coming spring season? Shitake plus Reishi? Echinacea? Zinc? What do you think?

Yes, all of these (and more, eg. pcygnogenol and nettle) have been used in the past for allergies.

The actives you mention all have properties in strengthening and balancing the immune system and hence, best started a few weeks before the hayfever season kicks off.

The problem that some find, however, is that these are not specific enough or do not always work in time and if this is the case with you, you might wish to consider something a bit more specific such as Pollinosan Hayfever tablets or Pollinosan Nasal Spray.