For me, it was a skein of beautiful handspun wool that I found 10 years ago on a visit to Orcas Island. It's pink with flecks of other colors, and has a beautiful texture, slightly irregular in thickness. I didn't do any yarn sports at that time, but I had to have it because it was so beautiful. I thought I might just hang it on the wall so I could look at it and touch it sometimes. Ha! Tried weaving (part of the skein went into stripes on a blanket), but the equipment takes up so much space! And time got shorter, but I still wanted to play with yarn! It turns out it is a lot easier to pick up and put down and pick up a crochet project. Progress gets made even if I only have five minutes at a time.
My avatar on this site is actually a drawing of my maternal grandmother in 1925 or so (from a photo taken about 25 miles from where I live now). She taught me to crochet when I was a teenager, but I wasn't very good at it. However, there must have been enough muscle-memory that making crochet stitches was a lot easier than knitting when I picked up that beautiful yarn again! I still can't (don't, won't) knit, really; why bother?!
She and my other grandmother both did beautiful thread crochet. In later years when her sight was not so good, she made dozens (hundreds?) of potholders from whatever on-sale acrylic my grandfather would bring home from Bartell's Drugstore. When he found some two-tone blue-green that we liked, he bought out the supply, and more than 20 years later, I still have five or six skeins of it. All of my relatives, and many of my mom's friends around the world (she was a travel agent) still use grama's potholders, and when I started crocheting again a few years ago, I was able to make my own. After all, they're the best! what would I do for potholders if grama's wore out?
In the non-crochet side of life: after a detour to New England, I'm back home in the Puget Sound area with my husband and two hilarious cats. I edit nonfiction for a living; my husband makes furniture [1] and has just started a woodworking school [2].
Links:
[1] http://timlawson.net/
[2] http://www.ptwoodschool.citymax.com/
[3] http://crochetme.com/forum/ego-booster
[4] http://crochetme.com/forum/just-got-book-plus-another-book