Most times having brown stuff coming out during your period is just old blood that happens during ovulation if you happen to be pregnant.
Brown discharge during pregnancy is also known as spotting which happens during ovulation during the middle of your cycle.
However if you're not pregnant then it's still normal to sometimes have brown discharge due to the change in color of the blood or older blood coming out instead of the normal read blood.
There's usually nothing to worry about if it stops eventually.