I made a mountain pillow the other day with things I found from the thrift shop. It was relatively easy and you can do it too!
Step 1: What you'll need + pattern cutting
I used: a green pillow cases from the thrift store, one small (10" x 30" or so) white & textured piece of fabric I found at the thrift store, a large sheet of newspaper for the pattern, a sharpie (a dark pen will work too), scissors, my sewing machine, some poly-fil, and an always trusty needle and thread.
First, you'll need to draw the pattern. I honestly just sketched one by hand. Cut it out and lie it on top of one of the pillowcases. Pin the pattern to the pillow case and cut.
Now cut the snow part off of the pattern, pin it to the white fabric and cut it out. (If you can tell, I cut two of them and that's only because I'm making two pillows.)
Step 2: Sewing
Place it over the green mountain fabric, pin and sew. Now pin the mountain fabrics right side together and sew, making sure to sew below where you just sewed so the stitches don't show when you turn it right side out. Also, make sure you leave part of the bottom open so you can turn it right side out. Now you need to cut the corners and trim the seam allowance so it doesn't get all lumpy.
Step 3: Stuffing! ...And you're done.
Turn inside out and stuff. Sew the bottom of the pillow by hand. You're done! Now you have a cute mountain pillow, made by things from the thrift shop!