Teasel growing in a wildflower / wildlife area with the graveyard at St Mary the Virgin.
en.wikipedia.org/wiki/Dipsacus
Teasel seeds are very important for small birds, like Goldfinches. The dried seed heads were traditionally used for raising the nap on woollen cloth.

The notice is a request not to strim or otherwise cut the area.
This zone is steeply sloped and curves around the west end of the church, and probably follows the line of the earlier enclosures. I suspect that the original church enclosure was more rounded, and the recent northern / western expansion has produced a squarer outline.