These suggestions are not meant to be too directive--there are dozens of paths to any given piece of the puzzle--but they may help some shorten the journey, if they want to shorten the journey or are being hassled by a determined small child full of that early-childhood curiosity.
1. At the bookstore: look in the children's nature section as well as the nature section, for a basic book on what you're trying to learn. Even a child's book on, say, "life at the pond" may tell you what your toddler wants to know, and give you a clear, if basic, idea of what comes next. In the nature section, look at the available field guides and see if you can recognize the things you already know (perhaps a cardinal, in a bird book, or an oak tree, in a tree book). You will probably find that one series makes more sense to you than another--and that's the one you should buy, no matter what anyone else thinks of it. Your first books in "learning nature" are starters--you may graduate to other books later, so don't worry too much about getting the "wrong" ones. Important: make sure any book covers the area where you are. A book on western birds, when you live in Massachusetts, won't help much.
2. Online: In the past 3-5 years, a lot of very useful online databases have begun to show up, some more useful to novices than others. Search engines are your friend in the wilderness, but you should know about a few of these right up front:
For insects and arachnids: BugGuide.net You can browse its huge database of images, and read its forums, without registering, though to submit a photo for ID, you have to register. But it's free and it's easy to use.
For dragonflies and damselflies: OdonataCentral It has state and county-level checklists, as well as pictures (but you have to click on the "camera" icon of a listed species to see the picture.)
For butterflies and moths: butterfliesandmoths.org Set up similarly to OdonataCentral, with state and county-level checklists.
In many other cases you can get species lists (or a guide to someplace where species lists are stored) by Googling on [statename] [county/area name] [what you want to know]. Sometimes it works better if you put the county or area name first, sometimes the state name first--you may have to Google more than once if you don't find something useful the first time. For instance, "Texas Williamson County native plants" or "southern Colorado birds". Notice the sites that host such things. These will often be sites hosted by universities, government agencies, or environmental organizations--and those will have other information you're going to want later.
3. Finding experts: Though you should try to figure out what something is from your field guide (it's the way to learn more and more about plants, birds, whatever) sometimes you'll be stumped. When you're stumped for more than 48 hours (and sometimes less) it's time to find an expert. Across the country there are experts in everything, and some of them (not all) will answer questions from novices. To find an expert, consider these basic sources: educational institutions (colleges, universities, science high schools), state and federal agencies dealing with plants and animals (county agricultural agents, state wildlife agencies, U.S. Dept of Agriculture, U.S. Fish & Wildlife Service), and nature/wildlife oriented organizations (Audubon Society, Native Plant Society, etc.) Yesterday I found someone to identify a snake from a not-great photograph of the snake by starting with a site hosted by the University of Texas (it's one I'd know about before.) There was a contact for "comments"--I emailed that, with a description of the snake and its behavior, and said I had some lousy images of it and would anyone be willing to look at it. That person contacted the snake expert at the Texas Natural Science Center for me, he emailed me, I sent the best images I had, and this morning the snake was no longer a mystery snake. I had been through three field guides and the online guide at the herps site without being able to ID it--it was easy and quick for the expert.