I read about mutton all the time. Mutton chops, a saddle of mutton, a leg of mutton. I know that mutton is sheep meat, and there aren't a lot of flocks of sheep in my area, but is mutton not a thing any more?
Not an answer, but you may not realize that (young) sheep meat is marketed as "lamb", as in lamb chops, lamb kabobs, leg of lamb, etc.
Edit: oh, if you could specify what country/region you're in, that could help people answer regarding sheep farming/marketing or the prevalence of sheep products there.
Edit2: I recall that there have been a couple of posts on this question; check out this post, which links to the other. Since both have been archived by now, if you have follow-up questions for any of the users, ask them here & mention their username to notify them
In the EU and US at least eating mutton is rare because of the potential risk of [scrapie] (https://en.wikipedia.org/wiki/Scrapie). After the transmission of mad cow disease to humans, with fears peaking around the middle 1990s, the risk (though small) of animal-human transition was deemed too great. This still has a significant influence on culinary practice today, though many restrictions on mutton and beef have been relaxed since the hight of the scare
The fact that the meat is tougher and requires stewing meant that it was always a less popular choice than lamb when lamb was available.