How do I know what Fruits and Veggies are in season?

Hello! How do I know what Fruits and Veggies are in season? I know some obvious stuff like apples and squash in fall, and watermelon in summer. But there are lots of produce that I'm not sure.... People say look at the prices, but I haven't been shopping for myself much - and when I wanted strawberries in the dead of winter - I'd buy them. Now I want to be a financially sound consumer... P.S. I live in the Northern Hemisphere - PA - USA....
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Citrus Carrot Salad

This is a variation of a recipe found on Chocolate and Zucchini. Citrus Carrot Salad 1lb shredded carrots (you can buy pre-shredded at the store) 2 oranges 1 lemon 1/4 cup brown sugar 1/2 cup raisins 1/2 cup shelled sunflower seeds Dump the carrots into a medium sized bowl. In a small bowl, squeeze the oranges and lemon to get the juice. Add the brown sugar and mix well. Pour the juice over the carrots and toss well to coat. Add the raisins and sunflower seeds and toss again. This is even better if you let the flavors meld overnight.
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