As far as stocking up on food goes, buy what you like to eat. But rather than just go out and spend$200 on food to stock pile, leave the $200 in the bank (hopefully earning some interest) and wait for what you want to go on sale - then take your money and buy what you want to stockpile. Also if you did lose your job you might be eligible for food stamps and the $200 might be needed for a car repair. That said, I am a big believer in an emergency food supply but do try to get some rock bottom prices. Essentials like pasta and canned tomatoes and oats, etc., go on sale at awesome prices regularly.
Clothes - you need to decide exactly what you need and then look for the item when it goes on sale or even better when you can get it at the thrift store or a yard sale. Make a list of what you think you really need and then hang on to your money until you can find what you want at a great price. End of season sales, maybe. I had a new winter coat for my dd on my list because her old one was pretty ratty and will be too small next year. I waited for ll bean's end of season sale and found a very nice jacket for 50% off . (I actually paid for it with a gift card from when I returned a pair of brand new (with tags) pair of kids snow shoes that I bought at a yard sale for $1. So her brand new coat essentially cost $1.
I think that learning to cast your thoughts into the near and distant future is very helpful when stockpiling. Learn to anticipate next year, next season, etc. I will actually stockpile kids clothes up to 5 years in advance and then I built up a big collection of clothes at rock bottom yard sale prices. When the time comes that they fit, I can just fill in the gaps with new purchases.
After a while, you won't even need to think about these things anymore. You just do it, just like washing the dishes every night. Sometimes stockpiling can be a big money sink or worse, a big money toilet. That happens when you stockpile things you could have lived without or that don't get used or that could have been purchased much, much cheaper.
Good luck and enjoy your tax refund!