There are at least two bands called Simmer:
1. an ambient punk band from Cheshire, United Kingdom (http://simmeruk.bandcamp.com). Their album, Yellow Streak is now available through Dog Knight Productions.
2. a short-lived indie band from the small town of Joure, The Netherlands (1997-1998).
Initially (and very briefly) called Slide and fronted by singer, guitarist and songwriter Theo de Jong, Simmer released one album, the critically acclaimed but commercially unsuccesful Mothertongue (1997).
Simmer (and Slide) frontman De Jong, previously released two albums with the more succesful band, The Serenes.