You can keep as much cash as you want at home legally in the US.
There are no laws that put a legal limit on the amount of cash that you can keep at home.
However insurance companies have a limit to the amount of cash that can be insured when at home which is $200.00 in most cases
Keeping a lot of cash at home can also be unsafe and insecure.
If you keep a lot of cash or any cash at home it's best to keep the cash secured in a fireproof safe that is also bolted down to prevent fire damage and theft.
You should also maintain an accurate documentation of any income sources you have and ensure the amount of cash you have at home matches your tax return.
If you don't and the cash does not match your tax return you could face a tax penalty up to 137 percent of the amount of cash that is discovered.
Also low enforcement can sometimes seize cash and claim the cash as proceeds of illegal activity.
Personally I would never keep more than a few thousand in cash at home and keep the rest in the bank.
You an also legally carry as much cash as you want as long as it was legally obtained and you are not restricted to traveling with sums of $10,000.00 or less.
In fact, you could travel with a checked bag stuffed to the brim with cash as long as you declare the amount beforehand.