Cactus Flower Id

It helps if it is known where the plant lives - Southwest US - or in a pot on the porch?

http://www.cactiguide.com/cactitalk/

Very knowledgeable people there who helped me correctly identify a cactus before.

Something in the Mammillaria family?

it could be a Rebutia,( Rebutia pulvinosaf f. albiflora) it will helps if you have another shot showing more of the plant.

Wish I could help...I looked through Google too, and my cactus pictures on my hard drive (with the names of some on them) but I can't come up with anything....thought it could be a "Feather Cactus" but it doesn't look 'feathery' enough... sorry

Thanks Mary, I looked through a LOT o images on google, still no clue on my part though.

I can ID a moving snake seeing a flash of scales though the weeds, but I am clueless with plants.

Got a book at home, JC, but I'm at work so somebody will answer before I can look. Just wanted to say nice shot....

Bumping for any cacti aficionados