Dark brown and glossy, chestnuts hail, unsurprisingly, from the chestnut tree. The meat of these nuts is hard to access through the tough peel; when you do, it has a uniquely starchy quality that can be eaten roasted, in purees or as an ingredient in stuffing. Chestnuts can be hard to find in stores, even around the holidays when they're in season, but luckily they can be replaced in recipes with common, or exotic, alternatives.
Other Nuts
Pecans or hazelnuts -- also called filberts -- can substitute chestnuts in stuffing recipes. Both have a crunchier texture and nuttier flavor than chestnuts. Pecans and hazelnuts blend well, though, with the flavors found in typical stuffing recipes, including sage, sausage and cornbread.
If you can't find chestnuts, chances are breadnut nuts will be even harder to track down. These come from the seeded version of the breadfruit plant, which grows predominantly in the tropics. The breadfruit has ample cream-colored starchy meat inside that can be roasted or boiled and pureed; the breadnut has less fruit but ample amounts of starchy seeds, appropriate for roasting, steaming and boiling. If you can find breadnut nuts, use them as you would chestnuts -- pureed or mixed with vegetables such as Brussels sprouts.
Fruit
Jackfruit is becoming really popular because it's flesh fits in well with vegan diets -- it's high in protein, potassium and vitamin B. The fruit from the trees, which thrive in the tropics, can reach 100 pounds. If you can find fresh jackfruit and penetrate its spiny exterior to reveal the fruity pods, you'll find seeds too. Boil the seeds for 10 to 15 minutes or roast them for 20 minutes at 400 Fahrenheit. The flavor and texture are similar to chestnuts, but slightly blander.
Vegetables
Tiger nuts come from a wild grass root that grows on the African continent. Known also as chufa seeds or earth almonds, tiger nuts offer a sweet flavor reminiscent of macadamia nuts. Their brown, shriveled appearance gives way to a chewy treat that's sometimes soaked to soften before snacking or mixed with dates and water to make a version of horchata_,_ a Spanish milk-like drink.
When peeled, the nuts are easier to chew and can be used instead of chestnuts in many recipes. Tiger nuts can be eaten as a snack just like roasted chestnuts; they're actually a root -- or tuber -- so they're even safe for people with nut allergies.