Define "farmer" look

The farmers I've known, including my brother-in-law, don't look any different from most other workers.  A pair of jeans and a work shirt, or a pair of overalls with a Tee or work shirt. Most likely a pair of boots. A "ball cap" most likely, though some like the effect of a cowboy hat.

Most farm worker figures I've seen are somewhat hokey. You might find a suitable worker figure, American style, in the Woodland Scenics line, but that makes you buy an entire set of figures to get the one you want.

John Deere hat? For a manufacturer, that opens up the can of worms of royalties.  Everyone wants a piece of the action, and to ensure that the product doesn't reflect badly on them.

Smaller scale John Deere hats...

It seems like in smaller scales (HO and N at least), you could likely get away with a green baseball cap and a rounded rectangle-shaped dot of yellow paint.  That lettering and the deer would be pretty tough to pick out with the naked eyeball at 3 feet or greater distance.

The farmers I've known, produce or dairy, tended to dress for the season and outside weather more than anything else. Boots above all except for the occasional pair of waders, jeans, work shirt, denim or heavier jacket, work gloves, hat if sunny and hot or rainy and cold.

Janet N.

Most I know wear Carharts for chores around the farm, especially

… when it’s colder so take any engineer figure, paint the coveralls a brown/tan colour, paint the cap green, shrink a decal to scale or just use a yellow drop of paint.

Instant Farmer. 

Woodland Scenics has

a number of "farmer" figures, some featuring overalls.

ETA: The 2051 economy pack is the one I would get, has plenty of "critters" as well.

Check 3D print vendors

You may have luck searching for some 3D printed figures. You have to paint them, but it is actually not too hard to do. I’ve bought from Printle (on Shapeways and Etsy) and MB-Model.com. I’ve also recently seen a company called ModelU (https://www.modelu3d.co.uk/product-category/finescale-figures/) that sells a variety of 3D print scale figures. And of course check figures on miniprints.ca .

I got this guy from mb-model.com it might make a good farmer figure.

miniprints

I think CustomCrews04 would fit the modern farmer look quite well:

https://www.miniprints.com/product/customcrews04/

Definitely consider 3D printing

I just picked up an AnyCubic Photon two weeks ago, and I've been having a blast with it. I've never done an resin (SLA) printer before, but I'd been doing FDM for several years. Details are quite crisp, and it's amazing that I can print as many figures as I want for $200.

For instance, here's a painted figure in front of an Athearn SD70ACe. Obviously not a farmer, but you get the idea of the detail:

Oh, and if you need to make people for 3D printing, there's a program floating on the interwebs called "MakeHuman". It's free and pretty robust.

Another alternative...

As model railroad shows and swapmeets have begun to populate the calendar in recent months, consider visiting your area shows & scour the swap tables for bagged non-painted (or painted) HO scale figures that you can paint yourself. Most of these bagged figures sell for a buck or two at most. A dab of modeling putty/bondo or a small sliver of styrene can be glued to the figure's forehead for a ballcap bill, then shaped with a hobby knife before painting. I did this method for a modern MofW crew gang with hardhats added using the aforementioned process above. I also reshape the figure's clothing with a sanding stick and jeweler's file to remove lapels from men's suits but retain the coattails for safety vests. For painting my figures, I use a toothpick to apply acrylics as I find it easier to control the paint flow.

Printed Figures from ModelU

ModelU is outstanding in technology and quality of 3D print reproduction.  But unfortunately the Pandemic put an end to plans for Alan Buttler, the owner, to expand the ModelU technology and business to North America.  The business in the UK has expanded so much that I doubt that they can cross the Atlantic for the foreseeable future. 

Check the website out https://www.modelu3d.co.uk/ to see what really can be done with modern technology. 

I have ordered a couple of times when I was still actively modeling a UK prototype and once in HO with a set of seated figures with a seated bald man reading a newspaper. I have had them a year but have yet to paint these exquisite gems. I have seen where someone photo-reduced a period newspaper and created a decal in 4 mm scale to date the model to July 1936. Printed railway details have been added to the ModelU catalog. Specials have included a set of pumpkin Jack-O-Lanterns and the 4 Ghostbusters.

The beauty of the refined scan technology of people in costume voluntarily posed at train meets and exhibitions or other events and 3D printed is almost a sculpting artform. The ragged Victorian series is a Dickensian delight. If most working ModelyU farming figures were wearing crushed fedoras instead of "peaky blinders" caps they would be perfect for US foreground farming scenes. 

Personally, I am looking for similar quality and technology for someone to print a early 1950's period North American people to specifically include a California PFE reefer icing crew performing the initial pre-icing of cars before movement to the packing house sidings. I have a diorama I would love to build around the Tichy 36" ice dock sitting on my future project shelves.  Generic figures were fine in the 20th century but we now have the ability to produce real reproductions of humanity to populate in still life our models with correct period and location figures.  

The next technology has to be moving hologram correctly costumed brakemen actually lifting the coupler levers on freight cars as they are positioned at a loading dock on a siding...