Yay! A topic where I might be able to help, not just get helped!
Based on the size of your pond and your locations, I would look at any pond plants as either annuals you can pitch in the winter or tropical or sub-tropical aquarium plants you can overwinter inside.
If you go with annuals, duckweed (a nice scale “lily pad”) or water hyacinth (not scale but gorgeous!) are cheap and fast spreading. The latter are, however, considered invasive and may be illegal to own in your state. You could also try “water lettuce,” and there are any of a number of fast growing aquarium plants.
Aquarium plants that grow in small pots such as Crytpocryne sp., Echinodorus sp. (“sword plants”), and various so-called “dwarf” and “chain swords” would make a lush carpet on the bottom. Taller species such as Vallisernia sp. and Aponogeton sp.will grow well but probably get too tall. There is also a cool dwarf lily called a “banana plant” that will send up some “lily pads.” All will have to come in before the first frost, and all will be a nice addition to any aquarium, though you will want to treat them for fish-killing parasites before adding them to a tank.
There are a couple cool epiphytic plants that you could try, too, such as “Java fern” and Anubius sp. Tie them on to a piece of driftwood or rock, toss them in the pond, and enjoy! Then pull them out, rock / wood and all, and plop them in the aquarium…after decontaminating them!
I have kept all of the above in indoor and outdoor aquariums with generally decent success. I am a very lazy fishkeeper, and I don’t keep anything that requires intensive care. Hopefully, you will find the suggestions above useful.
Eric