What can I take to jail with me for a 30 day sentence?

Not much. At a county detention center, you essentially bring yourself and whatever you are wearing. Jewelry comes off and goes into a property bag. Personal clothing is typically replaced by facility-issued clothing. Any cash gets processed and applied to your account. Personal hygiene items from outside are usually not permitted in intake because the facility controls what products are brought into the housing units.

For a 30-day sentence, the honest answer is that the facility is going to hand her what she needs for basic hygiene through either commissary access or an indigent kit, and the rest of her belongings stay outside until she walks out. There is nothing personal worth worrying about bringing in for a stay this short.

The more useful preparation is on the outside. Make sure someone trusted is looking after anything that matters, that bills and obligations are covered, and that there is a plan for the 30 days. The property question is the least important part of getting ready.