Death cap mushrooms in California have killed three people, and left more than two dozen poisoned, as officials continue to issue warnings to foragers in the state.

Sonoma County health officials issued an advisory on Thursday to not eat wild mushrooms after the death of a man, who consumed them last weekend.

Throughout the state, there were 35 cases of wild mushroom poisoning, resulting in three deaths and three liver transplants, between November 18 and January 4, according to the statement.

Normally, fewer than five cases throughout the state in total would be expected.

'Early rains and a mild fall have led to profusion of the toxic death cap mushrooms in Northern California,' said Sonoma County interim health officer Dr Michael Stacey.

On December 5, the California Department of Public Health (CDPH) said that cases of poisoning were linked to foraging of wild death cap mushrooms.

The death cap, also known as the Amanita phalloides, looks and tastes similar to edible varieties, such as field mushrooms.

The advisory warned that even cooking, boiling, drying, or freezing will still not make the mushrooms safe to eat.

Death cap mushrooms (pictured) contain amatoxins, which can cause gastrointestinal symptoms, such as diarrhea, nausea, vomiting, abdominal pain and dehydration

The East Bay Regional Park District said: 'The best way to stay safe is to ensure that no mushrooms are consumed by humans or pets'

The warning was echoed days later by the East Bay Regional Park District, highlighting that death caps have been cropping up in large numbers in its parks.

'I wouldn't trust myself to go out and pick mushrooms of any kind right now because it really takes an expert to be able to make a differentiation between a poisonous mushroom and a non-poisonous mushroom,' said Dr Stacey to KTVU.

Additionally, Julie Schreiber, a nationally known mushroom expert, foraging leader, and educator, told the outlet that there have been tons of mushrooms in people's yards this year, leading more people to collect them.

'I personally took a mushroom identification class about 35 years ago, and I've been foraging and teaching people about foraging for a long time, and I also teach people about cooking and eating mushrooms, and I still feel like there's a lot that I don't know,' said Schreiber.

According to CDPH, death caps contain amatoxins, which can cause gastrointestinal symptoms, such as diarrhea, nausea, vomiting, abdominal pain, and dehydration.