Well I somehow missed your last post that you live in an apartment. Still most of my suggestions you can do if you have access to a park. Even the camping one, often these are offered in city parks routinely. I would recommend you check your local city's website if they have one and you might find some activities you didn't even know were offered at local parks and such.
If there are any nearby farms, sometimes they will also hold classes that are very organized and all you have to do is show up and pay the fee and attend with your child. This might be a fun option for you too.
And yes, walks around your neighborhood would be great!!! Maybe keep a nature journal too. This can be at your child's level and ability. I was just putting away my two 6YO's nature books from this last year. Oh, what a keepsake! Even they were saying their first drawings from last summer wrere so different from what they are drawing now, but it was fun for them to see how much their nature journaling has improved.
If they wanted words with their drawings, I would write it for them or spell it for them. They just started reading simple words recently, so often they would narrate to me and I would write it for them. Amazing to read what they saw even at 5 and 6 years old!
I just bought 5x7 blank journals for them last year at our local curriculum fair. I used these books this last year. My son had the one with the animal cover and DD had the butterfly cover.