There are many patches of these things in the grass around Lyneham wetlands, they are very small and i cant zoom in any further with my phone. Im guessing they are a a fungus or myxomete.
This is Physarum cinereum, a cosmopolitan species which loves to grow in grassy areas. Gardeners often think there is something a miss, but this species will not harm the other plants at all. In fact, in its amoidoid form it is consuming bad bacteria and other bugs in the gardens.
To be 100% accurate with ID to species all myxomycetes require microscopic examination. Its also a good idea to collect samples and lodge at the herbarium.