is this an autism trait or not

I quite enjoy ruminating, sometimes it's a bit annoying, but overall I like thinking.

SS, maybe you need to know because it's stepping on a mental bug?

I have a similar issue. In my case, it often seems to revolve around actors, musicians, or songs. For example, sometimes I'll watch a film and I recognise an actor, but I can't remember their name. It will bug me to the extent that I will search online for the name of the film, so that I can then look for the name of the character they are playing and find out their name. I cannot relax until I know, but I can almost always guarantee that within a day or so of reminding myself of the actor's name, I'll have forgotten it.

It's even worse if I hear a song that I like, but I don't know the title of the song, who sang it, or what the lyrics are (it's the music I tend to focus on, more so than the lyrics).

I find myself thinking, "Why do I need to know, when it's not important in the grand scheme of things, and I know that I'll just end up forgetting it anyway?!" 

Yes!

I get words stuck in my head and it's very very random and irritating

The phrase "how much would you pay?" Is a recurring irritant. It has no meaningful context at all but at times of stress it reappears when I try to distract myself from the stressful thing. I've recently begun to think it might be a kind of stim. The only pattern I found to these phrases is the rhythm is always a mini ritardando eg. "How much would you pay" is a triplet followed by a duplet. Another one "the number four" is an anacrusis quaver, two quavers and a crotchet. I wonder if this is my brain trying to calm itself.

I know this is not the same thing as your experience but maybe your brain is finding the thought of the circular argument somehow reassuring?

I do it as well. It's quite a common autistic trait. I'll find myself dwelling on things that happened years ago, and even just go over utterly inconsequential nonsense (usually when I'm trying to get to sleep). I can end up turning stuff over and over in my head to the point nothing actually gets done.

So don't worry; you're not alone in this.

I think first and act on that, then feel afterwards (sometimes).

Most people feel first and act, then think afterwards, sometimes. Mostly thinking is cursory and forgotten.

This explains a lot of the confusion and problems. It also explains why no amount of detailed consideration really solves the problem, because it is not a logic problem. If you are trying to manage other people's emotions, knowingly or not to avoid conflict, you end up wrong footed and confused, and eventually exhausted.

Definitely agree, I feel like I have to find out the when what why and how of things. 

It can be problematic when trying to get to the bottom of why certain things happen in human relationships. Humans don't seem to apply logic to lots of there interactions, emotions are involved and it gets complicated. This is when I have to write the thought down in my journal and close it. It does seem to help.

That's useful to know, thank you. I get this all the time, even when I'm doing something I enjoy and want to focus on it. Sometimes I think of a phrase or a snatch of music and it keeps looping. It can be anything, usually mundane things or sometimes annoying repetitive thoughts about what I've read in the news or seen.

Yes, I do share that as well. I do ruminate a lot but I don’t think thinking about an acorn applies to rumination. This is more like obsessive thinking and it can be related to anything. Acorns, space, a mattress, a game or glasses... I get obsessed with thoughts all the time that are totally unrelated, of a very simple nature (or not) and they can stay in my head for hours. It’s exhausting cause you know they are sometimes even ridiculous. Some other times they are not ridiculous at all.

Oh, I almost forgot to answer your main question: yes, I think it’s an autistic trait but I’m not sure if shared by a majority of autistic people or by some but definitely autistic and or very ADHD as well.

NAS78944 said:

can anyone tell me if this is an autism trait or not.  often i get thoughts in my head and i go over and over them and i cant get it to stop.

This sounds like rumination, a common autistic trait:

https://www.simplypsychology.org/autistic-rumination.html

Autistic individuals might often find themselves stuck in negative thought loops that are difficult to break out of, also known as rumination

I don't think the thoughts need to be inherently negative but the inability to break the loop can make it negative in its impact.

It is only my take on the subject.