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You're probably not aware of it, but there could be a gold mine in your backyard!

No, we're not talking about the Eureka-gold-nuggets-whisker-faced-prospectors type of gold mine; we mean more of a take-advantage-of-what-the-land-provides-to-make-a-little-extra-spending-money type. And some of these outdoor projects even hit the home trifecta: easy, fun, and lucrative!

Here are some ways to get started.

Make good with wood

Estimated earnings: Hundreds or thousands of dollars per tree

If you have densely wooded property full of hardwood trees such as birch, oak, or mahogany, there are companies that will come out and thin those trees, harvesting them for timber, and pay you to do something you might have paid someone else thousands of dollars to do instead. A website called SellYourTrees.com makes it all very easy.

Use your yard clippings

Estimated earnings: From about 20 cents an ounce

Yard clippings and kitchen waste can be surprisingly profitable when converted to compost and/or fertilizer. There are plenty of videos and books available that can teach you how to treat your plant-product waste. And yeah, you can even worm your way into some serious coin, as resourceful Princeton classmates Tom Szaky and Jon Beyer did by starting their own worm bin, which produces rich, organic, liquid fertilizer from insect waste.

Their company, TerraCycle, now sells its wares at ubiquitous stores such as Home Depot and Wal-Mart, and has developed numerous recycling products that can help you do the same.

Be a sap

Estimated earnings: Up to $15 per pint of maple syrup

Retired teacher Dick Henderson of Thunder Bay, Canada, realized all the sap from his huge maple trees was going to waste, so he decided to tap the trees and make maple syrup. Although he uses it for his own purposes and gives the rest away, plenty of others bottle their sap and sell it to tourists and gift shops. Delicious!

Horn in on the antler industry

Estimated earnings: $1 per inch of antler

If you live in an area where elk roam wild (e.g., Colorado, Wyoming, Montana, or Utah) and you come across a nice rack (elk shed their antlers once a year in early spring), they could provide quite the windfall.

"Sheds," as the antlers are called, are a hot commodity to people who use them to craft furniture and lamps, or want a source for all-natural doggie chews. They can sell at retail for several dollars per inch.

Kevin Foutz, a rancher in Colorado, notes that "hard bone" brokers are easy to find on Craigslist. And by the way, Foutz says if you have a ranch dog, you can train it to find and retrieve antlers.

Get in a jam with fruit

Estimated earnings: Up to $12 per jar

If you're fortunate enough to have fruit trees, try bottling or canning what grows on your premises. Homemade jams sell at a premium in fancy country stores, and lemon curd happens to be all the rage right now. Tomato sauces and bottled apple pie filling are also popular. You can sell them at farmers markets or in upscale food boutiques.

Get in the swim

Estimated earnings: $10 to $35 per lesson

If you have a pool, you can have a classroom. Take lifeguard, water safety, and swimming instruction classes at the local YMCA or community college, and voila! You can teach those little tadpoles a thing or two about how to behave in the water. Many parents would prefer private lessons in a quiet place with fewer distractions than they'd find at a public pool.

Provide parking space

Estimated earnings: $35 to $100 per month

Here's an idea that doesn't require trees, grass, or a green thumb. As a matter of fact, if your backyard is all cement, it's even better. Offer to store someone's boat, RV, or extra car. If you have a covered area a vehicle will fit under, you can charge even more.

Grow your own … anything

Estimated earnings: $5 or more per plant

We know what you're thinking, and at the moment there are 23 states where that is legal, with certain stipulations. But there are plenty of other high-cash crops that you might not have thought of and require little space, including ornamental succulents, catnip, saffron, truffles, and mushrooms. Granted, your yard may need to meet special requirements in terms of sun, shade, and moisture, but there's essentially a cash crop for any type of land, so be sure to check.

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