Google actually have a special search engine for US patents at https://www.google.co.uk/advanced_patent_search but it doesn't seem to have much luck finding this one.
A bit of fiddling reveals that each patent has a URL based on it's number though, and I believe https://www.google.co.uk/patents/US804529 is what you're looking for:
Be it known that I Minna B. Foster, a citizen of the United States, residing at Sausalito, in the county of Marin and State of California, have invented new and useful Improvements in Stock-Supporters, of which the following is a specification.
My invention relates to a device which is especially designed for supporting stocks of soft material, such as are used by ladies for neckwear.
and so on...
A PDF of the original can be downloaded.
The above answers are entirely correct, but since you already have the patent number, you can also just go straight to the source - the U.S. Patent Office! They have a bunch of different ways to search patents (see various options here: https://www.uspto.gov/patents-application-process/search-patents#heading-1), but the easiest in your case is to just go here: http://patft.uspto.gov/netahtml/PTO/patimg.htm
Then just enter the patent number and search. The patent by one M.B. Foster comes right up.
Free Patents Online is another resource. The patent you're looking for was the first match given by entering 804529 in the search field. Images are available by clicking the "download PDF" link on http://www.freepatentsonline.com/0804529.html .