Monkeyflower is a brightly coloured flower for damp ground / pond edge. It may not be strictly native but grows wild in the Black mountains which is good enough for us. It looks great when mixed with other wetland plants such as Purple loosestrife and Ragged robin.
Monkeyflower is a good nectar source for bees and butterflies
It can self seed prolifically into odd places all over the garden, not just pond edge! Therefore ideal for developing around a pond, and small seedings can easily be removed from other areas of the garden.