Found this plier of sorts. 6.5" long. Only writing on it is PATD across top jaw. Serrated jaw slightly curved. Was it used to stretch carpet/upholstery? Any ideas what it was designed for?

Might help if we saw just a tiny bit more of it.....

Sorry, thot I had all the pics attached. Will try again.

I would go for upholstery webbing pliers - the webbing is gripped in the toothed jaw, and the bent section acts as a fulcrum, allowing the webbing to be tensioned with one hand whilst being tacked in place with the other...

Cobblers (shoemakers) use a similar version but with a much narrower jaw, often with a built in hammer head - the technique is similar, but once stretched over the last the leather is held in place by the hand, and then the pliers used as a hammer to tack it in place...

Upholstery webbing pliers is what it looks like to me as well.  As Billman pointed out, cobbler's lasting pliers have a similar function, and canvass stretching pliers serve the same purpose in stretching canvas over frames for paintings.

I think I have a pair of the pliers Billman49 is talking about. They are marked R. Timming & Sons England. I was wondering what they were for.

Yep, "lasting pliers."  Osborne still makes these, and they come up from time to time on eBay.  I've got three antique examples.