These are both annuals, very attractive, but each year have become more numerous, to the point that they are growing over everything else. Try to limit their rambunctiousness so other species have a chance.
Tickseed Sunflower (Bidens sp.)
Big show of yellow flowers in September. Goldfinches feast on the seeds in October. Gets tall, so can be pulled out if too close to trail or covering up other desireable, less abundant species.
Jewelweed
Orange, tubular flowers that hummingbirds feed on throughout the summer. Explosive seed pods. Related to garden Impatiens. This year, jewelweed is verging on too much of a good thing, growing in thick stands up to 6 feet tall. Worth pulling out if it’s covering something else up or crowding the trail.
White Vervain (Verbena urticifolia)
[Here is] a photo of a plant growing here and there along the trail that looks a bit like nettle but is actually white vervain (Verbena urticifolia). The species name is latin for "leaves like nettle". It has lots of little white flowers on top, and opposite leaves along the stalk.