Cat behavior question for cat people

It was hot today as I cut my lawn, 92 and humid, and I'm sweating like a pig pushing my mower I notice about 25-30 feet away in the shade near the house next door is this cat just laying ( lazing ) there, looking at nothing in particular but occasionally at me as I mowed back and forth. It definitely wasn't the next door neighbor's cat and not wild as it didn't bolt soon as it saw me. I shut the mower down, took a short break and drank some water and when I came back out, the cat was still there.

Before I fired it up to mow near the area it was in ( and would no doubt scare it away ) I figured I'd try to make friendly contact. I trod slowly toward it crouching as I went and as I got near, it rolled over on it's back, stretched out with its front paws clawing at the grass in a sort of "scratch my belly" gesture. I noticed it had no collar or tags of any sort on it, and looked ( to me anyway ) too well nourished to be a stray. Every time I pet it though it meowed loudly. Not purred, meowed, loudly, in a slightly distressing sounding ( to me ) tone. I'm thinking, "what am I doing wrong?" and "what's wrong with him/her?" Yet still allowed itself to be petted and continued to roll about on the grass like it wanted to be petted. I left it be and it just lazed/relaxed their until eventually my mower got close enough to scare it to move further away: not a bolt in terror, more of a "I don't like it here, I'm moving away a bit".

What do think the behavior means? Do you think it's a very trusting ( or stupid ) wild/stray, or just a domesticated cat without a collar?

Just curious. Always have been about human and animal nature, though I'm not a pet owner ( not since leaving home at 21 or so )