State nonprofit laws usually address nonprofit governance matters. However, you can choose different rules, as long as they don't violate state law and are included in your bylaws. If you choose to follow state law, restating them in your bylaws will ensure that all your operating rules are in one document.
Bylaws are not public documents, but making them readily available increases your accountability and transparency and encourages your board to pay closer attention to them. Your board should review them regularly and amend them accordingly as your organization evolves.
According to the IRS' compliance guide for 501(c)(3) nonprofits, "An exempt organization that is required to file an annual return must report name, address, and structural and operational changes on its return." That means if you change your bylaws, you have to let the IRS know on your next annual report (990). Organizations that do not have to file an annual return may also report these changes to the IRS' EO Determinations Office. Some states may also require you to file bylaws and report changes.
To find sample bylaws, try an Internet search for "nonprofit bylaws" plus word(s) that describe your nonprofit (e.g., youth, environment, church). For example, "church nonprofit bylaws".
Please note that bylaws are very specific for each organization, so you will want to change them to meet your own nonprofit's needs.