The subtle sounds of the forest right after a rain. The drops of water falling from the tree boughs and hitting the foliage below with a nice fat plop. Its just peaceful.
The sound of a baby puppy barking for the first time! DAWWWWWW
trains. wind in the morning. birds in the morning. snow falling when its eerily quiet. bong water bubbling. a chick breathing heavily during sex. cats purring. rain falling on car windshield
Similar to what other people have said: Falling asleep to thunderstorms, waking up to thunderstorms or wind, and when it's snowing really hard with no wind and every sound is dampened significantly.