Kylie Jenner I Got the Best Dirt $5 Mil Can Buy!!!

Kylie Jenner just threw down millions for a very well-placed pile of dirt, and it's the first sign the mom-to-be could be looking to expand ... TMZ has learned.

Kylie scooped up the plot of land adjacent to her $12 million Hidden Hills home for a cool $5 million ... ALL CASH! The corner lot is about 1.5 acres, and we're told the plan is to turn it into a garden and possible barn with horses since there's a ton of horse trails nearby. Although nothing's set in stone yet ... the purchase gives KJ plenty of room -- 3 acres when combined with her current crib.

She could also build a badass playground for that baby she's got on the way.

As we told you, the Kardashians just signed a new $150 million TV deal -- and while the elder sisters are getting a bigger chunk of the deal, Kylie's obviously more than making due.

Kylie's go-to realtor, Tomer Fridman of Compass, helped her seal the deal.