It is commonly referred to as the silver spike, but its actual name is the Silver Sickle.
Named for its crescent shaped cap (resembling the agricultural tool known as the sickle), the cap also hides a bit of a surprise, it is razor sharp. Ranging from dull oxidized silver tones to glistening silver mimicking the finest sterling silver found.
The Silver Sickle is rated 5, useful but use with caution. This toadstool uses this razor sharp cap to protect itself from fungi hungry predators. Remember when using this toadstool, that once the cap is removed from the stem it should be used within 13 hours, or the cap will become unstable and could result in a dangerous explosion.
The Silver Sickle usually prefers to grow in open areas like meadows, along the banks of rivers or on the edges of rivers and lakes. You will also commonly find them near low ground covering brush which may offer a bit of shade, and a bit of a break from the elements. These toadstools do not grow well in severely cold climates or overly wet conditions. Even controlled greenhouse growth studies in locations like England and Scotland have not ended in outstanding populations. It seems these toadstools are affected by the outdoor weather, even when grown indoors.
The best way to harvest Silver Sickles is to use a simple field sickle with a basket placed below the toadstool. Lop off the cap and it should fall easily into your awaiting basket. The caps are the portion you'll want, as the stems are not good for much except mulch for your garden gnomes.
When diluted the toadstools make an excellent magical growth regulator, working to either increase or decrease your desired item to the size you calculate your potions for.