I know many of you see these all the time, so you see one and think, there goes another one - I'm thinking about you Larry! :)
But I haven't seen one in at least 10 years! I can't image how this one got here, since, as far as I know, we don't have any members of the cabbage family growing at this time of the year. Cabbage, turnip and collard greens, broccoli, etc. all grow in winter here. I plan to research it and see if there is some member of that family that could be growing here now - if you know, please let me know!
It's very hard for me to make pictures of sulphurs, and I had the same difficulty with this white butterfly. But I had to use one of the many I took -