Down's Park is an incredible place for your wedding, the Mother's Garden is perfect for a ceremony, hardly any decor is needed, the natural scenery is beautiful. There is power at the garden area so a dj won't be a problem. We were allowed to decorate with shepherd hooks and candles, the area was clean and free of debris when we got there.
We also used the Brightwater Pavilion for our reception. There is no power, so music can be a problem unless you have an acoustic band/singer. We were able to use a portable speaker system which works fine if you have someone to man it. No generators are allowed, no amplified music, ect. Park is not flexible on this at all, so don't bother asking. Candles weren't an issue in the pavilion, you aren't allowed to use any nails or tacks to hang items, you have to get creative if you want to be able to hang items, we were able to use wire to hang the things we wanted, just wrapped it around the support that was there and it didn't damage anything.
Pavilion was clean when we arrived, park rangers were very helpful, and once everything was set up didn't bother us at all.
I highly recommend the Mothers Garden at Downs Park as a excellent venue for Wedding Ceremonies, the garden was in bloom, the Chesapeake Bay was shining, it could not have been a more beautiful location for a wedding, and the price is right too.