Your first stop would be to contact the Passaic Co Historical Society. They look to be well organized and you can find information on their collections on their website. If they do not have what you're looking for, they should be able to direct you to who would have those records (likely the city or county for land records). It looks like they're willing to do fee-based research, but they also have many resources online.

This is a question you might consider cross-posting to /r/genealogy. They lot of genealogy is learning about local history and finding what records have survived, and locating them.

I'm not sure what kind of information you are after exactly, but /u/Littleanomaly gave good advice in reaching out to the Passaic County Historical Society. In fact, there is a PDF online that summarizes many of their library/archival holdings. The Passaic County Historical Scoiety (PCHS) had (has?) a newsletter entitled The Castle Genie and this article from the newsletter gives some further information about the cemeteries in the county. A brief blurb about the history of each of cemeteriy is included in the article. From that and from some other online resources, it appears that the two cemeteries you are wondering about are old family cemeteries no longer kept up, many of the tombstones having since been removed, and bodies re-interred elsewhere.

Luckily, both cemeteries' tombstones were transcribed many years ago, when the cemeteries were still active. The Holland Cemetery's tombstones were transcribed in 1949 by J.D. Quackenbush, Jr. The cemetery is also known as the First Holland Cemetery, or the Vermuelen Cemetery, after the family who it originally belonged to. Quackenbush was quite prolific in New Jersey and southern New York in transcribing cemetery records - since many of them have since been removed, his transcriptions are often the only resource left.

The other cemetery, the DeGray-Ryerson Cemetery, was first partially transcribed in the 1882 book History of Bergen and Passaic Counties, New Jersey... by W.W. Clayton, starting on page 562. That same chapter of the book, starting a few pages earlier, gives a history of Manchester Township. Until the early 1900s, Hawthorne was still part of Manchester Township, so this history should give you an idea of the early town's history. This book, in general, appears to be a rather thorough local history of Passaic County.

But back to the DeGray-Ryerson Cemetery. Some online sources say that a more complete transcription was done of the cemetery in the 1910s or 20s. So, if you look back at that PDF for the PCHS's library holdings, and look under the section for "Cemetery Records", it looks like the PCHS does have the transcriptions for both the cemeteries you're wondering about. The Holland Cemetery is listed as the "First Holland Cemetery", and the DeGray-Ryerson Cemetery is listed as the "Hawthorne DeGray-Ryerson Cemetery". So, if you contact them, they may be able to provide you the transcriptions, or where to easily find them. (Or not. They may just be in a book in the library that isn't digitized, though often if you ask nicely for a look-up of a name or two, the volunteer at the historical society will help you. In these days of COVID, you might have to wait, and the more urban the historical society, the less often they have the time to do look-ups voluntarily.)

Beyond what the PCHS has in their library holdings, another valuable resource for you will be the Family History Library in Salt Lake City, Utah. Or, rather, their online presence, at familysearch.org. Sign up for a free account and they have many more records that you can search through for free. After signing in, at the top of their website, click "Search >> Catalog". On the next page, type in "Passaic" in the "Place" field. The dropdown should suggest to you Passaic County, NJ, as well as the city of Passaic in that county. Pick the county, and then select "Search". (You can also search for Hawthorne, in Passaic County, although most of the relevant holdings are related to the county, not the town.)

On the search results page, FamilySearch organizes their holdings by topic. If you click on any topic, you'll see what holdings they have related to that topic. Click any of these, and it'll give you more information. Most of these are microfilms or books, and some of these have been digitized. You can browse through the digitized ones directly there on the website. Some are un-digitized, though, and you'd have to actually physically travel to the Family History Library in Salt Lake City to consult with those resources.

I'll just go through what seems to be most relevant to your research. The following list is all of government records:

Land And Property:

• Deeds, 1837-1927

• Mortgages 1837-1866, with a more extensive index 1837-1916

• Assignments of Mortgages 1851-1908

Naturalization and Citizenship:

• Declarations of intention papers, 1837-1870

• Declarations of intention, 1873-1906

• Naturalization papers, 1837-1906

Probate Records:

• Letters of administration and guardianship, 1837-1903

• Orphans Court records, 1837-1900

• Probate records, 1837-1902

• Will dockets, 1837-1900

• Wills, 1835-1911

Vital Records:

• Marriage records, 1837-1893

• New Jersey, Passaic County marriage records, 1837-1902

All of the above are digitized and browsable on FamilySearch. They all come from microfilms of the original government records. You may notice that many of these records begin in 1837. That's because that's the year Passaic County was formed, out of land from Bergen and Essex Counties, NJ. If you want information and documents from before 1837, you'll need to start researching pre-1837 records from those counties.

Also of interest will probably be the three books on cemeteries in Passaic County, two of which are digitized and browsable.

There are also many church records in the area, which will often be your best bet in finding birth/baptism, marriage, and death records before the late 1800s.

And then there are several books under the "History" topic that will give you a more general history of the county. One is the aformentioned book linked above by W.W. Clayton. Another is the 1899 book The News' history of Passaic from the earliest settlement to the present day... by William J. Pape. FamilySearch doesn't have it digitized, but Archive.org does.

A third book is Historical sketch of the county of Passaic, New Jersey, especially of the first settlements and settlers by William Nelson. FamilySearch, Archive.org, and Google Books don't seem to have a digital copy of this, but Ancestry.com does. Of course, you need a subscription to Ancestry to access it, but check your local library (at least, when it re-opens after COVID). Many local libraries have subscriptions to Ancestry, so if you go to your library, you can access the book for free that way.

Beyond the PCHS and the FHL/FamilySearch.org, another resource you may want to consult is the State Archives of New Jersey. They have a section detailing their Genealogical Holdings. So a lot of government records that aren't held by the PCHS or at FamilySearch will be held there. Some records can be requested for a fee; if you can get to the NJ State Archives yourself, you can do a lot of your own research as well.

Each county's County Clerk will also have their own collection of records. Here is Passaic County's County Clerk. The Clerk of Courts--which is a different office--usually has court records. However, in both cases, after 95 years in New Jersey, the records are supposed to be transferred to the State Archives. So, anything from before 1915 should be in the State Archives now, and if you request any records or research from the County Clerk before that date, they'll probably just refer you to the State Archives. (Whether or not the State Archives actually has or can even locate the record you're looking for is another matter.)

Some other resources you may want to consult:

• Public libraries in Hawthorne, and in Passaic County will probably have their own set of microfilm and other records that might not be held elsewhere. Search their online catalogs for relevant holdings. In general, most large public libraries do have a "Genealogy" and "Local History" section.

• University libraries in the town, county, and state may also have some unique holdings.

• The New York Public Library also has pretty extensive holdings on the local history and genealogy of metro New York City, New York state, as well as northern New Jersey.

• Back on FamilySearch, if there is a particular family you are interested in, you may try searching by "Surname" instead of "Place". It will give you a list of books/other holdings related to that family. Be warned that not every genealogy book is created equal. Some are incredibly well-researched. Others are just somebody who didn't footnote anything, and didn't cite sources, and a lot of the research is bad and/or out of date.

• The Genealogy Center at the Allen County Public Library in Fort Wayne, Indiana, is probably second to the Family History Library in Salt Lake City on the extent of genealogy holdings in the United States. If this library is convenient for you to get to, you might consider making a trip. It certainly is a distant second, but it's worth having on your radar, at least.

The above is more focused on late 19th/early 20th century research. Going back further, there are other records you may want to consult, especially before 1837 when Passaic County was formed. So, again, I recommend you cross-posting this question to /r/genealogy. Not only will they be able to suggest resources I may have left out, but if you have any specific questions, usually somebody on that board can point you in the right direction.

I hope this helps. Good luck!

As a rule of thumb, I would advise you to look for a town hall archive or its equivalent. Cemeteries as usually under public control, so records are plausibly within the dependencies of local administration. A public library as well could possess if not proper documentation and registries, some copies of previous works written or containing articles and the like on this topic.

If your area has one (I am not very familiar with the American bishops' organization), contacting the nearest ecclesiastical administration could help, since cemetieres usually have a connection to parishes for the record of births and deaths, at least in the Catholic Church. Usually dioceses are very likely to keep ancient records (writing from Europe, my local diocese has documents dating from the 13th century). Also, an ecclesiastical administration could tell you if these people buried there were part of some lay organizations which cared for the burial of its members, possibly leading you to records which could however be held in private archives.

Lastly, there is the possibility that some documents could exist within the cemeteries themselves as part of their administration. This last case might result in a sort of private archive which could be not as easily accessible a public one.

Unfortunately I'm not from the US, so I may have missed on the organizations that may contain some informations, but I hope this general idea helps.