Another interesting thingfun pastime we had in the countryside decades ago was watching movies in the fields. Another fun pastime we had in the countryside decades ago was watching movies in the fields.

I suggested some new vocabulary that makes the meaning clearer and sounds more natural. For an activity you enjoy, "fun" is better than "interesting", because people often call something "interesting" when they don't actually like it much but don't want to say anything negative, so if it's used in a place where people would normally say "fun" etc. it can sound not so good. Pastime = a fun activity/hobby you do to pass the time.

Another interesting thing in the countryside decades ago was watching movies in the fields. An interesting thing in the countryside decades ago was watching movies in the fields.

Since this is the start of your post/passage, "Another" doesn't make sense to use (since there was no "other" interesting thing before this sentence). (It could work in the Title, since it would be able to reference previous posts)

As I mentioned in a previous passageost, we kids liked to sleep on the threshing ground in the fields on summer nights. As I mentioned in a previous post, we kids liked to sleep on the threshing ground in the fields on summer nights.

As I mentioned in a previous passage, weas kids, we liked to sleep on the threshing ground in the fields on summer nights. As I mentioned in a previous passage, as kids, we liked to sleep on the threshing ground in the fields on summer nights.

Usually, a town had a projection"movie team", with about three people. Usually, a town had a "movie team", with about three people.

"projection team" isn't really a phrase in English. Some words that come to mind are: film crew/squad/team/group theater crew/team/group I added quotes "" around "movie team," since "movie team" is also not really a phrase in English, but it fully describes what you're trying to say, so you can just treat it as a "fake phrase" that still conveys what you're trying to say

They had a set of projection equipment, including a generator. They had a set of projection equipment, including a generator.

This is more correct, but "movie equipment" sounds more natural

So when a village wanted to show movies, they would contact the town’s projection"movie team" and pay the fee. So when a village wanted to show movies, they would contact the town’s "movie team" and pay the fee.

Back ato the threshing ground—, once we heard the generator, we’d get really excited and try our best to make out which direction the sound was coming from. Back at the threshing ground, once we heard the generator we’d get really excited and try our best to make out which direction the sound was coming from.

An em-dash "—" is more used for an "aside," which is something that can be fully removed from the sentence and the sentence would still make sense. Since you were later talking about "the direction the sound was coming from," you can't put "once we heard the generator" as an "aside". em-dash "—" Examples: I've been eating strawberries—which is unusual for me—and they have been making me happy! I finally beat that game today—though I guess it wasn't actually that hard. (You can't end an "aside" with a comma "," only with another em-dash or sentence ending mark (.?!))

When we finished watching the movie and headed back, it was usually midnightIt was usually midnight by the time we came back from finishing the movie. It was usually midnight by the time we came back from finishing the movie.

This sentence order feels a bit more natural. Mostly, my issue is with using "and headed back" (which is a continuous action) with "it was usually midnight" (which is a time that something should have been completed).

We felt tired but happy. We felt tired but happy.

Correct, but a more natural suggestion: "We felt tired, but were still happy"