Carex pilulifera; The Pill Sedge can be the few sessile female spikes concentrated just under one upright male spike. It grows in rather dry conditions (dry grasslands, dry heathers/scrubs). It is common in some regions of Iceland but missing in other. It can be found in eastern Iceland and north-western, western and north-western regions of Iceland as wel as some other locations in the north and south. Alas, I have not seen it yet on Iceland so the photo's are from elsewhere, but gives a good representation of its appearance. They will be replaced as soon as I have made photo's of this particular sedge on Iceland.
The Pill Sedge (C. pilulifera) is a member of the sedge family (Cyperaceae). The Icelandic name of this species is Dúnhulstrastör.