Autumn Mushroom

I went for a walk at Warnham and walking back through Benland Wood, a group of four mushrooms were seen. They looked somewhat sinister and I've no idea what they were. Evidently they may not have smelt too good as there are flies in and around them. The cap on this appears very thin as it is fully opened. Overall there were very few fungi to be seen despite the wet conditions and the ludicrously warm conditions for the time of year.