Earthball species

Description:

Growing near some boletes and under some deciduous trees. I was excited by this find because I thought it was too dark to be a Common Earthball. http://mushroomobserver.org/141943 S. cepa? http://www.wildaboutbritain.co.uk/forums.... i went back a month or so later and found a few more (see 5th and 6th photo), I assume they're the same species

Notes:

fx - i have a sample