I live in MO. The mushrooms are brown and smell. Last year my flower garden was very nice and this year I don't know what happened.

Smell could also be from skunk or cat spray

Mushrooms tend to thrive in very moist / humid environments it could be due to the weather being different unlike what you experienced last year, most likely hotter, with more light showers. I suggest you water the flower garden in the early morning so the heat from the sun doesn't let the water condense and create a moist, humid environment that gets trapped in by the flowers like what a canopy in a forests does. Also prior to doing this dig up about 3 to 4 cm of top soil around the flowers ofcource because the soil density lowers the waters absorption rate therefore leaving some moisture on the top to condense also creating humidity. This i am certain will fix your mushroom problem and once the mushrooms are gone i am certain the smell will disappear also due to the mushrooms being fungi and most fungi have distinctive smells in majority unpleasant.

Don't know where MO is? But reason can be 2 things.You have a virus in soil. Or you have watered the area too much. Inviting smelly fungus. Dry off soil, if neccessary get fungus killer from garden center. Take in piece of it to center, and they will advise you. Good Luck!

Is it mulched, or was there a dead tree there ? The fungus needs a food source , so when that is exhausted, the mushrooms will be gone . Are you watering a lot ? Let it dry out a bit between waterings.

ps MO = Missouri, correct?

overwatering
rule of thumb...one time a week, for one hour, early a.m. in your area twice a week for 30 mins each time would work nicely.

hope this helps