stone – la piedra

(Pronounced pee-eh-drah)

To remember that stone is pronounced pee-eh-drah (piedra) in Spanish, use the following mnemonic:

A lord threw a stone at a rat as it crossed the chamber - all the peers said the rat (piedra) problem needed sorting. 

Piedra is feminine, so it's la piedra. Imagine a lady carrying a giant stone in a weight lifting contest.