When you search using only keywords and no filters, eBay's search finds listings that contain those keywords in the title or item-specifics. If those particular keywords are linked to a specific category, the search may be automatically sent to that category, but if not, then any listing with those keywords in the title or item specifics could potentially be returned.
There are some other possible quirks involving keyword substitutions or spelling corrections, and eBay may remove some results by default if you are doing a sort by Price plus shipping: lowest first, but otherwise the matching operations is fairly straightforward: either a listing contains those keywords or it does not.
So if you search for micro machine spring with no other limits, your results will include lots of Micro Machines from Toys & Hobbies and a few items from Clothing that also include those keywords or close substitutes.
You could limit your search to just Toys & Hobbies to avoid the clothing results, or try searching like this to find matches for the actual name of the product you are searching for:
micro-machines spring
https://www.ebay.com/sch/220/i.html?_from=R40&_nkw=micro-machines+spring&LH_TitleDesc=0
Why aren't spring flowers in the results?
If there are spring flowers listings that also include micro and machine in the titles or item-specifics (or that include a close synonym), your search should find them.
eBay's search does not know what your intentions are -- it just knows how to match keywords in titles and item-specifics. If you ask for listings that contain those three words in any category, eBay will find listings that match, even if they are not what you had intended.
