Here are four reasons to crash Yarnbombing Los Angeles’s monthly knitting sessions. 1) A homemade Valentine’s Day gift is worth more than anything downloaded and sure to get you a higher return. 2) The free sessions are cathartic and cheaper than therapy. 3) You can learn the latest guerrilla textile tactics being employed to warm up L.A.’s stark urban environments. 4) If your project doesn’t pan out, the museum’s gift store sells terrific global trinkets. More information.