This is a pattern for a garter stitch square.
The square is knit diagonally, from a corner.
With your choice of yarn and knitting needle: cast on 1 stitch. Turn.
Row 1: In that one stitch, knit in the front and back. (2 stitches)
Row 2: Knit the first stitch, knit in the front and back of the next stitch. (3 stitches)
Row 3: Knit 1, Make 1 right (pick up the stitch below the next stitch, knit it, then knit the stitch on the needle = M1r) knit the last stitch. (4 stitches.)
Row 4: Knit 1, M1r, knit to end of row. Repeat this row until square edge is desired width or length.
Knit 2 rows even. Then begin decreases.
Row 1: Knit 1, k2tog, knit to end of row. Repeat this row until only 1 stitch remains. Bind off.
NOW, here comes the fun part.
Option #1 ~ This baby blanket was knit of acrylic sport weight, of one square. I worked it until it was about 40", then found a lace garter edging that I like and trimmed it using more of the same acrylic.
Option #2: Shawl/lap robe, pretty much the same as the baby blanket, except worsted weight yarn was used. I really liked this one because the variegated looks very nice as a garter (hides the pooling) was super soft.
Option #3: Stash busting! ~ Adventure Afghan
I like this option a lot. Sometimes you just end up with bits of things that don't necessarily make enough of anything. In this case, had a lots of bits of never been used acrylic, worsted weight yarn, of different brands. I made these squares following that same pattern at the top of this post, until I had 80 stitches, then decreased. As each square was finished, I put them in a pile, which eventually filed a milk crate in my stash. The squares I carried with me to work on every time I left the house, riding along while my husband drove us to the store, went to the movies, went camping. They became my adventure squares, I knew when the blanket was done which one I'd been working on when I saw the last of the 'Harry Potter' movies, the last trip we took our dog on before she died... When I assembled the blanket, I did the last bit where our grandson was watching my work and told him about the squares, enough for everyone to pick a favorite, which was mine, which was Grandpa's.... about the adventures I worked on while I knitted the squares, my hopes for it with him, that it would keep him warm in winter, that he would take it on his adventures, that he would still be using it when he went to college.
I am working on another square now. I think I will do a variation on it, make a rectangle. One edge will go until it is 48" the other will continue until 60", then decrease. I'm planning to donate it to the local Linus Blanket project. It's one of those Pounder skeins from the craft store, in a dark sage. Hoping some foster boy will know it was made just for him to grow strong and free as the forests. Stay tuned, I hope to post the finished picture of it here.