See this image, a large heavy stone may be laid accidentally on his toes
squash [transitive] to press something so that it becomes soft, damaged or flat, or changes shape
squash something/somebody The tomatoes at the bottom of the bag had been squashed.
Move up—you’re squashing me!
squash something against something He squashed his nose against the window.
squash something + adj. Squash your cans flat before recycling.
Note: The object may not fall from a higher position onto his toes. The object may be so heavy that when he drag it & push it he may accidentally lay it on his toes. And, sometimes his toes may hurt but not to a level that the toes become damaged.
Crush is more often used for hard objects, like "I crushed the soda can." Squash is usually for soft things like fruit. "She squashes the rotten mangoes."
However, the dictionary says "Unfortunately some of the flowers got crushed when we were moving them.", so I assume "crush" can be applied for softer objects such as flowers or grapes.
Ngram says "crush it" is much more common than "squash it".
How do we express it "Be careful!, The stone may squash your toes"?