Looking for wellies (calf-high 'farm' boots), galoshes (slip over the footwear you wear as an outer protective cover), or something like duckboots (waterproof boots designed for mud/marsh/wet)?
LL Bean (there's on in Marlton) has plenty of different models of duck boots (they call them "Maine Hunting Shoes") all the way up to 16". They're durable, breathe more than rubber wellies and have laces that help keep them on your feet. I usually call my order in when I buy them and have lace hooks put in instead of eyelets for like $1.50 extra. They're made in Maine, so that's a bonus. The only downside is they aren't easy on/off.
For galoshes, Tingley are the best I've used and I believe they're made in USA as well.
For wellies, I prefer the European made brands like Le Chameau, Aigle, the higher end Hunter's etc. They're expensive but the materials used (natural rubber instead of PVC), the linings (leather, neoprene etc), the fit and the soles all add up to a boot that you can wear comfortably all day.
For a throw-it-in-the-rig-and-forget-it kind of welly, LaCrosse boots are decent enough.