I was somewhat inspired by the Yarn Harlot's darling watermelon baby hat to go dig in my stash and find the yarn that I bought ... oh, a year and a half ago, maybe? ... with the intent of making my daughter a watermelon hat.
On my head:
(This is my daughter's hat, but her head's not that much smaller than mine.)
On the bathroom counter:
And a closeup of the edging:
Yarn: Plymouth Encore worsted, about 1/3 to 1/2 skein of the hot pink and just a few yards each of the white, light green and dark green
Beads: Black opaque pony beads, about 35
Gauge: 5 st/in in stockinette, on a size 7 needle
Pattern: made it up as I went along!
Lessons learned: Norwegian purl is lovely for doing corrugated ribbing (knits one color, purls the other), but it's a bear on the first row, when you're purling into the opposite color and keep getting the stitch you're manipulating tangled with the working yarn of that color; better to 2-hand it for that row, and switch to the Norwegian purl thereafter.
Things I'd change: I'd swap out which color I used for which stitch on the ribbing; doing the purls in the dark green would make them flow better up from the cast-on row, as well as obviating the problem I mentioned above, and light-green knits would flow better into the light-green stockinette above than the purls did.
Things I loved: Using beads instead of duplicate stitching the seeds in was a great idea; I'd have made this hat long ago if I'd had this idea earlier. They really pop, they're all shiny like real seeds, and I didn't have to deal with a million ends. I used the crochet-hook method to put them on, which was simple and fun. The biggest challenge was keeping the placement random and not letting them fall into a gridded pattern; I really enjoyed this, and it kept what might otherwise have been a boring project interesting and challenging.
How to knit it:
Measure your target head, and subtract a couple of inches. Multiply that by your stitch gauge. Round to the nearest multiple of 4, and cast on that many stitches in dark green on a 16" circular needle. Knit 6 rounds of 2x2 corrugated ribbing, with the knits in light green and the purls in dark green. Break off the dark green, and work a round of knits in the light green; if your stitch count is not divisible by 3, increase or decrease as needed during this round to make it so. Knit 1 round of 2 light green, 1 white. Knit 1 round of 1 light green, 2 white. Knit 2 rounds of white. Switch to hot pink; from this point until the end, you will place beads as desired, using the crochet-hook method -- do them randomly or regularly, your choice. Knit until the hat is about 2 inches shy of the desired total length (for many people, this will be equivalent to the length of their hand, but it doesn't work on *tiny* kids, whose heads are disproportionately big), but err on the side of too-long if you're uncertain, since too-short hats are irritating. If your number of stitches is not a multiple of 7, 8, or 9, do a couple of decreases, evenly spaced, during the last couple of rows, so you get to a number which is. Whichever multiple you're using, place that many stitch markers, evenly spaced, as you work the last even row. To decrease, work to 2 stitches before a marker, then k2tog, and repeat that around; do these decreases every other row until you're down to 3 stitches between markers, then skip the even rows. On the row where you k2tog around, take the stitch markers off. Break the yarn, thread it on your tapestry needle, run it through the remaining stitches, and pull tight. Weave in ends.
ETA: For those who feel more comfortable with an actual pattern, I've written one up and posted it to my blog, Let me explaiKnit; it's in the sidebar. Happy knitting!