plants for my ducks

[Esthersducks]

I have a mallard(or i believe it is called a caller or call duck?) And a cayuga/runningduck (mom is a cayuga and dad was a runnerduck) and i have a run for them but i think it is to small so i'm going to expand it. For some landscaping a would like to put some plants in there but i don't really know wich plants are the best for ducks (i'm afraid that i will accidentally buy poisenous plants)
Sorry if the english is bad, i'm from holland so not the best in speaking (typing, lol) english, hope you understand!