Depends on what state you're in. I forget the exact language, but the state I'm in has a mandatory form you have to fill out when you sell that has a whole section on "buried rubble used as fill material". Doesn't matter the amount, next homeowner digs a hole to plant a tulip bulb and runs into a some chipped concrete and brick, and I didn't disclose it.......and if you do disclose, most buyers will make you remove it. Unless you're way out in the sticks and no one's going to care about a pile of brick in the back of your 40 acres.

Which led me to....every trip to the dump include 4-5 milkcrates full of chipped concrete, tile, and brick tipped into the construction waste dumpster. Took a few months, but beat the hell out of paying for a few dump truck loads.