I have also witnessed hummingbirds investigating stop signs and red ice chests. The attraction to anything red is a learned behavior, not instinctive. Red buckeye is a native shrub that is blooming now and illustrates the type of flower that hummingbirds prefer. The flowers of red buckeye are long, tubular and red. This shrub blooms at about the same time the hummingbirds are coming back from their winter sojourn.
Hummingbirds are a major pollinator of red buckeyes, so the bloom time is no coincidence.
It is easy to attract hummingbirds to your own yard. Plant a variety of nectar-producing flowers and supplement them with a hummingbird feeder. Feeders should be cleaned at least once a week to prevent mildew and bacteria populations from forming. If you don't clean your feeders regularly, you may be harming the very birds you are trying to attract. If you grow a good variety of flowers in your garden, you will almost certainly attract hummingbirds.