What are these ?

Hello,

I've just had the biggest 'crop' of mushroom/toadstools over the last couple of days , the large cream coloured ones started off as balls and over one night they changed to the saucer shape. The brown coloured ones just 'spring up' overnight and have popped up all over the lawn and garden, we've never had so many in our garden.

Has anyone any ideas just what they are and will they damage the lawn and flower beds, my wife is the keen gardener and I'm just the hedge cutter and lawn cutter person !!.

Thanks in advance Neale.