Buy a book or find a guide online that is specific to your area. It's a lot easier than us trying to tell you.
Take your book or guide to a nice place to forage, and start trying to identify plants and see what you have in your area, then do more in depth research into plants to see what benefits they have. Then start picking/cutting.
Mushrooms scare me albeit, so I haven't foraged any (except some chicken of the woods that grew in my yard). That one I'd like to learn from someone in person
There are tons of different winter foragebles regardless on if you live in the tropics or not. Not as many foragebles in summer or spring sure but there is a decent variety of wild plants and mushrooms to choose from.