Mercury is in everything we eat. It's not possible to live on the planet without ingesting it. Here are detected levels of mercury (all harmless) found in foods tested in Ottawa, Canada:
eggs 1.50
lamb 2.30
cottage cheese 0.97
cheddar cheese 1.02
beef steak 1.80
chicken and turkey 1.80
bran cereal 1.40
donuts <0.14
wholewheat bread 0.18
rice 1.80
beans 0.22
broccoli 0.67
carrots 0.47
celery 0.50
mushrooms 5.10
tomatoes 0.28
cherries 0.26
plums 0.30
milk 0.25
fish 24-69
corn 0.21
raisins 0.68
honey 0.16
beer <0.05
baby cereal 0.35
pizza 0.15