Count vs. mass — where can you look this up?
Most English dictionaries used and published in the United States don't include that information, just as they don't provide IPA-based phonemic transcription. However, dictionaries published in the UK and elsewhere sometimes do, especially dictionaries for English learners.
One American online exception is Merriam-Webster's Learner's Dictionary, which dutifully reports that pea and bean are both [count], while rice and sand are both [noncount].
Beware broad-brush approaches, even if you find a dictionary offering the count – uncount classification. Some – perhaps many – nouns are non-count in some senses and count in others. Coffee is a good example – its basic sense is uncount:
Coffee is a drink made by infusing the ground beans of Coffea arabica etc.
Too much coffee can be bad for you.
However, different products will be count:
Coffees produced using a higher proportion of robusta beans in the blend tend to be bitter and have less flavour but better body than those with a higher proportion of arabica beans.
And ellipsis produces another count-noun polyseme:
Two coffees, please.
(ie two cups / mugs of coffee)
Rice is count when different strains are meant, and sand when different sorts are being mentioned. (There is a poetic use of sands also.) Even furnitures is allowed in certain situations.
There are also grey areas – you'd probably ask for less peas rather than fewer peas (especially if they were mushy) on your plate. Non-count doesn't always mean that counting would be impossible - confetti is treated as a singular non-count noun. The difficulty ensuing when one tries to use algae in both count and non-count senses has recently been addressed in a different thread.
A good place to start looking is http://learnenglish.britishcouncil.org/en/english-grammar/nouns/common-problems-countuncount-nouns .
You should try Wiktionary. It lists the plural, or indicates that the noun is uncountable. For example, rice is listed as uncountable, and bean has the plural listed as beans.