When I make a pincushion I try to fill it with emery sand (not always possible) because it's so good for sharpening my pins. I buy emery sand on Amazon or etsy.com so it's super easy to get and one pound of emery sand goes a long way. You only need a little emery pincushions to help sharpen those pins.
These teacup pincushions (I used the idea from a blog called MrsMMakes, link here) are filled with polyfil because it was the best material to get the nice plump pin cushion top on the cup. I did cover them with wool (another good material to use for pins). The pink cup has wool felt I bought in squares from an etsy seller. The blue pincushion and the green pincushion are covered with felted wool I knit myself. To make the blue and green covers I just knit a quick square of stockinette stitch from my wool yarn stash, felted it, filled it with polyfil, sewed it up and glued it into the cup. The teacup is then glued to the saucer. This is a super quick and fun project and they would also make a great gift for a fellow sewist. The hardest thing about making these pincushions was finding a not too expensive pretty teacup and saucer to use. I always go to ebay or etsy for my teacups and I try to buy them out of season like early in the year before Mother's Day and well before Christmas because the prices go up for those holidays.
I have no idea what is inside these tomato pincushions I bought, I think it is sawdust, but I don't think my sewing room would be complete without a tomato pin cushion, or two or three. I found the following information on wikipedia regarding these cuties: "According to folklore, placing a tomato on the mantel of a new house guaranteed prosperity and repelled evil spirits. If tomatoes were out of season, families improvised by using a round ball of red fabric filled with sand or sawdust. The good luck symbol also served a practical purpose—a place to store pins. Typically, the tomato is filled with wool roving to prevent rust, and the strawberry is filled with an abrasive to clean and sharpen the pins."
I made the little wool pincushions with yarn I had in my knitting stash. I posted how I made them here.
I made this big crazy, wonky pink pincushion with wool felt that I filled with emery, the best of both worlds. It's really heavy and great for using at the machine because it's low profile and it doesn't get in the way of my sewing.
I bought this felted wool pincushion because it's so pretty.
I have a few more pincushion projects that I want to make. There is a completely cute pincushion made using a 3" embroidery hoop, the tutorial is here. And I know I really, really, really need a very cute ring pincushion to have for my hand stitching sessions, and that tutorial is here.