Knee high, waterproof walking boots - think Toggi, but a different, cheaper brand (still just as good so far!). We take the dogs out for walks a lot in the forest and by the sea, and we have recently got an allotment too, so they're fab. I have been up to my ankles in mud/puddles before and my feet have remained bone-dry. Like wellies but much comfier.
Same for my Seasalt Coverack rain coat - I was sceptical with the price but I waited for a sale and honestly, it's fab. It can be absolutely pelting it and I'm still dry underneath as it has taped seams, and yet I don't start to feel clammy in it the way I usually do in other waterproofs. I got it in a khaki green and am now hoping they bring out black again too as it has slowly crept from being just my "out walking the dogs" jacket to my "any time it might possibly rain" jacket...
I think I'd be remiss not to mention our allotment itself too actually - £75 a year and we've got 250 square metres including about 20 existing beds, an established walnut tree, a cherry tree, a small shed (with lots of tools and gardening gloves etc. left in it!), among other things... I grew up without a garden and we haven't bought a house yet so having our own place we can put a stamp on and grow fruit and veg is lovely, even if all we're doing for now is preparing for spring planting.
Lastly (I think?), an Owala Freesip water bottle. I have had several different types and brands as I am terrible for drinking water otherwise. I work in healthcare and this is the only one I've found so far that is insulated, has a straw lid and handle, AND a lid that covers everywhere your mouth would possibly touch when drinking.