I'm assuming she's a lady. Sorry I couldn't get a better picture but she was not a willing subject. She's in her web underneath the lip of this pot. She's a very pale yellow, with a little black design on her back. I've seen lots of others crawling around in the soil this year -- similar, but maybe not identical if I remember correctly, that have black legs and perfectly spherical yellow-white bodies.
This spider appears to be in the family Theridiidae (cobweb/comb-footed spiders), but the image is not clear enough for a specific identification. Have a look at the image at http://tinyurl.com/25mdqug to see if the overall shape is consistent with yours.
Thanks -- that's very close. This one doesn't have quite as many black markings as the one you linked to, but I'll bet they're related if not exactly the same kind.
