Here's a set from Waltzingmouse:
Blessed by You | Waltzingmouse Stamps
Also, she hasn't come out with anything new in awhile but Renee Mullins of Plum Purdy Designs might have something you'd like:
Categories at Plum Purdy Design
She has stamps in clear and unmounted.
Cornish Heritage Farms had a line called "The Rummage Bin" with some prim style stamps that you may be able to find second-hand. And there used to be a company called "Saltbox Studio." I have many of their sets and you may be able to find them used as well.
Whipper Snapper Designs has some:
Primitive Folk Sheep - Fourth of July - Holidays - Rubber Stamps - Shop
A search only turns up 3 on Whipper Snapper but I know there are more.
I had a couple of prim Christmas stamp sets in my shop but they are now only digital, perhaps stamps again in the future.