The frogs!
Every summer, beginning about July, the frogs in the various swamps and ponds around here start croaking. It’s total background bliss for about two months. So easy to fall asleep to with the windows open and the warm country breeze blowing through the house.
The tick-thump of clothes tumbling around inside the dryer.
The lurching stops of the mail truck working its way down your street.
The calypso clank of riggings on beached catamarans at dusk.
The murmured fantastical conversations of kids when they’re playing alone.
Thunder from cloud-to-cloud lightning, that seems to roll on for minutes.
Another one for that lonesome train whistle (well, horn) in the distance, late at night.
And another for steady rain on the roof, also late at night.
A Merlin V-12 aircraft engine.
Mourning doves.
All the sounds of sailing; from the gentle slapping of water on the hull on an early morning, to the creeks and groans of the rigging and lines under way in a hard wind.
Deep burble of a V8 exhaust.
Pop/snap of a lid from a fresh jar of pickles.
Sound of snow falling late on a silent night in the mountains.
Delicate sound of thunder.
Driving rain against the windows.
“You’re were right.” 
My gf’s favorite sound is the peepers in the evenings. Apparently in our area they’ve just begun recently. Eventually I’ll hear them, but even with my hearing aid they aren’t something we can enjoy together just yet.
The earsplitting crackle of fighter planes passing by in full afterburner.
A Formula One race car running a hot lap. Not one from the past ten years, with the crappy little V8 engine; I need to hear the 3-liter V10 from the early 2000s, spinning at unholy RPMs.
Thunder that shakes your lungs and makes you feel like the earth will split in two.
A woman breathing/moaning in ecstasy.
One kind of original one…and one really weird one
Running water. Particularly from a fountain or over rapids
I also enjoy a hard steady rainfall (I had one a couple days ago…my door was open, I heard the rain while playing video games…oh it was just perfect)
Here’s the kind of original one: The sound of higher speed trains going over tracks. The rhythmic tchck thchk thchk that it makes as it’s speeding along
Here’s the weird one: A brush running through a girls hair. An old college girlfriend of mine used to have really long (almost waist length) hair, and the deep reverberating sound the brush made as it was going through the tangles was so neat to me.
That crossover “starting to distort” tone a journeyman guitar player can coax out of a tube that’s just about to give it’s last breath when he’s working into a great blues lead.
The sound of a dog getting a drink of water.
The clip clop of horse hooves
The jangle of a charm bracelet
Someone writing on a chalkboard (no nails, please)
Golf on tv
Fog horns in the distance
Car tires on gravel
Mopar starter motor
Morse code
I was wondering how many posts would go by before this, one of my first thoughts.
Bagpipes.
No really.
The old cartoon sound of a plop in the water.
The clacking of poker/casino chips being shuffled(real clay chips and not the plastic ones you find in home games).
The jangling of golf clubs in the old style leather golf bags.
Wow, forgot about this one. A band of pipers with well-tuned bagpipes belting out Amazing Grace.
I also like French horns, especially when they’re in an orchestra with 5 or more of them.
I like the little chirruping sounds cats make.
I like the songs of song sparrows.
I am also a fan of bagpipes - maybe because I’m 1/4 Scottish?
Tight 4 part harmony
Kids playing
Owls on a dark night
The sound of a large, well-trained choral group singing Ode To Joy from Beethoven’s 9th. Every year in Portland they get every singing group in the city that is willing together to do that concert. It’s stunning.
The squeak and crunch when walking on dry snow in extremely cold weather.
Well-executed harmony.
Oboes, bassoons and clarinets.
The thundering of a large waterfall.
Exhaust rumble of a high performance engine.
I love the voice of the announcer on the Prague Metro. It just makes me feel all calm and happy.
Apparently I’m not the only one who likes it, going by that video.