We live in the Pacific Northwest, so these ideas for homegrown infusions will mostly work for our area, but they can give you ideas about what you can grow, or gather, wherever you are for the future. The best way to have delicious infusion materials available is to gather herbs and flowers that appeal to you all year long and dehydrate them, pack them in jars and store them in a dark, cool, dry place or you can reuse the black bags that our tea comes in, and just store them in a cool place.
Since it is winter now, I will concentrate on things that can be gathered and used today. Try:
Candy Cap Mushrooms
Mint or Sage
I even found some Roses, but I know it's something special and unusual this time of year. Rose Petals are always wonderful in herbal infusions, they add color and flavor.
Once you gather these things, you can make your infusions with the fresh herbs, or dehydrate them and keep them for later. If you can, I recommend that you use a dehydrator, but if not, you can try putting in the oven at the lowest setting for a short period of time spread out on a cookie sheet.