It is probably stuffed with poly dacron loose batting and sewn closed.

Your choices are: A. Make your new cover and stuff it in there. You can razor off the cording if it shows/feels through. Be aware that that print might show through your new cover. If so, you can line your new cover with muslin.

Or: B. Measure your pillow across the belly, cord to cord, add seam allowances (usually 1 inch both ways[for 1/2 inch seams]) and make a new pillow that size. Buy your new stuffer in the next larger size (for fullness). It can be very helpful to cut your new back an inch larger both ways. That makes for ease of completing your construction.

Or find ready made pillows you like to replace them.

I'd take a close-up pic of the fabric of both the chair and one pillow that you do like with my cellphone, and head off to TJ Maxx, Marshalls, Kohls, Tuesday Morning, etc. to look for one that works well with them. Super easy. From what I've seen, you can easily get a beautiful one for about $20. And then I'd donate the alphabet pillow to Goodwill.
Lynn

Hit Home Goods! Save your time.

Bed Bath & Beyond sell toss-pillow covers -- they're usually near the slipcovers. I've seen some at Lowe's hardware stores, too, so if you have either of those stores nearby, take your pillow's measurements and you might have some luck.

Or, making an "envelope pillow" is pretty simple to do, using iron-on tape to secure the folded down "seams" and adding a snap on the back.

Beyond those, I'd do what Lynn suggests. Home Goods does seem to have a lot of toss pillows nowadays!

Going the Home Goods route *would* save my family the anguish they feel when they see me pulling out my sewing machine. ;) Thanks, everyone!