I lived in CA for a while and the one thing i wish I had done was visit the redwood trees. Tons of state and national parks there. Well worth the time. Take a swim in the ocean. Be prepared that it will be colder than you expect. A snorkle and mask and some flippers will make it even better. Try surfing if you can.
Peterson's guide to wild edible plants is a personal favorite.
Learn how to identify and use wild plants within your area. There are many edible species that grow wild and in abundance; this is a practice that essentially every human generation prior to this past century was skilled at yet it is becoming a lost skill. Get a guide to edible plants and spend time out in the wild learning to identify which is which. /r/whatsthisplant is also a good resource for identification and there is a large (20k+) group on Facebook which is an excellent resource full of knowledgeable gardeners and naturalists.
About 2 years ago I started really getting into wild plants, sense then I have learned many plants edible, medicinal, and poisonous.
this is where I started https://www.amazon.com/Field-Guide-Edible-Wild-Plants/dp/039592622X/ref=sr_1_2?ie=UTF8&qid=1465766026&sr=8-2&keywords=petersons+field+guide along with youtube.
A Peterson's guide has drawings of inedible plants next to the edible plants, and the drawings point out differences between the two. It's really helpful. Plus they have color plates. They have a guide just for North American edible plants.
I start with easy plants.
There is a series of books you can buy as a set from David Canterbury, starts with a broad and basic book called "bushcraft 101," and has specialized books for more advanced topics like medicine, food gathering, etc.
That, and a localized Peterson's guide to edible plants.
https://www.amazon.com/stores/page/CFBF422A-0B2C-46CB-A272-7AED8BC49A42
Two books i regularly bring with me are this for edible plants and this one for medicinal plants, between the two i haven't come across a plant i couldn't identify. IIRC Peterson makes a mushrooms guide too. I'm unsure how good it is because honestly getting a mushroom ID wrong scares the crap outta me to the point id rather just steer clear.
One tip- plants are easy to spot when they are flowering, but you may not always be foraging when they are in bloom. What i do every spring (and thru the fall) is go out with a notebook and the aforementioned books, and just search for stuff in bloom, and jot down when it blooms, where i've come across it (environment they like), and what the plant looks like besides the flower. Then ill keep an eye out and try and ID the plants when they are no longer in bloom. After a few seasons of doing that it started becoming second nature.
This one is a great one. https://www.amazon.com/Edible-Wild-Plants-Eastern-Peterson/dp/039592622X
I highly recommend the Peterson Field Guide to Wild Edible Plants. Amazon link
I would reccomend the Peterson Field Guide to Edible Wild Plants and the National Audobon Society Field Guide to Northeastern Trees
That's what I've been using and enjoying but a lot of people would reccomend a local expert before you (if you decide you want to) eat a wild plant. If you want to know the uses., other than eating, that a plant has than I'm not so sure how to help with that as I've never really seen a book be specifically about that, I'm sure one exists but I havn't seen it. I learned a lot of stuff through the internet as well, it can be really helpful I find.
https://www.amazon.com/dp/039592622X/ref=cm_sw_r_cp_apa_fabc_XePPFbQZXXBH1
Peterson's North American edible plants. All hand drawn illustrations of plants, loads of info. More about idintification than growing though.
I have two on my list that I am excited about. One is about Edible Plants. The other is paracord projects. Both are on my Amazon Wishlist. I can't decide which one I want more.