Inhale

to breathe in something:

 She inhaled (the fresh air) deeply.

Gravel

very small, rounded stones, often mixed with sand:

Gravel covers the driveway.

Crunch

to crush hard food loudly between the teeth, or to make a sound as if something is being crushed or broken:

 She was crunching noisily on an apple.

 The gravel crunched underfoot as we walked up the path.