Coiled Baskets

To weave a coiled basket from grasses (pineneedles, rope, etc...) tie a loose knot in one end of the grass. That will be the center of the bottom. Using the center of this knot as the anchor for your stitches, just keep adding grasses, and whip-stitch them into place. Try to keep your stitches in an ever-growing spiral, like this:
When you begin coiling, use inexpensive cotton twine or similiar. Polly would work too, and won't fade in the sun light. As your ability improves, choose better twine for the stitching: ideally, waxed linen. When your twine gets too short to make more stitches, just tie another piece on using a square knot plus a half hitch...otherwise the knot may slide out over the waxy twine. Try to put your knot either on the inside of the basket, where they won't be seen, or better, between one row of coils and the next (so that it can't be seen from the inside or outside of the basket). Once you begin actually making this type of basket, all answers to any questions will become evident.
Another way to begin this style of basket is to wrap thread around a washer, completely covering it's surface with dense stitching...then just start adding the grass or pine needles on the outer surface of the washer. My mom finds this easier than tying a knot in th grass.

Another idea is to find a pretty cabochon stone, rubber cement a piece of leather to the bottom of it, let it dry, poke holes around the outer edge of the leather, and anchor the grasses to it.
Some weavers use a hollow piece of cow horn or short piece of PVC pipe as a "gauge" to add the grasses with. This is especially helpful if you are making a large basket with large coils. It helps keep the density of the coil consistent.