It's about as heavy as a Raindrop
(a.k.a. drop, a.k.a. droplet) (average)
The weight of a raindrop depends heavily on the type of weather, but averages about 3 grains. The familiar teardrop shape of a raindrop is actually an optical illusion, caused by the reflection of the light and the motion of the drop.
It's about one-fourth as heavy as a Nail
In other words, 3 grains is 0.25 times the weight of a Nail, and the weight of a Nail is 4 times that amount.(for 15-gauge, 2-inch, finishing nails)
A two-inch finishing nail weighs 12 grains. Nails have been in use for more than 5,400 years and were ven used as a medium of exchange in ancient times.
It's about one-fifth as heavy as a Jelly Bean
In other words, 3 grains is 0.18 times the weight of a Jelly Bean, and the weight of a Jelly Bean is 5.6 times that amount.(for Jelly Belly beans; approximate)
Made of sugar, corn syrup, and pectin, a single jelly bean weighs about 18 grains. President Ronald Reagan cited jelly beans as his favorite candy and 49,000,000 grains of the candies were served at his first inauguration in 1981.
It's about one-tenth as heavy as a Paper Clip
In other words, 3 grains is 0.14 times the weight of a Paper Clip, and the weight of a Paper Clip is 7.1 times that amount.(average)
Notwithstanding the tremendous variation in sizes and materials, a typical paperclip weighs about 22 grains. The country of Norway has used the paper clip as something of a national symbol since the end of World War II based on the erroneous notion that the paperclip was invented by a Norwegian, Johan Vaaler. However, the paperclip had already been in existence for at least 30 years by the time of Vaaler patented his paperclip design.
It's about one-tenth as heavy as a Playing Card
In other words, 3 grains is 0.11 times the weight of a Playing Card, and the weight of a Playing Card is 9.1 times that amount.(ISO 216 B8 size, 2.5" x 3.5")
A single ISO 216 B8-size playing card weighs 28 grains. Although this size is the most common home playing card, many casinos use "bridge size" cards — 2,640 sq. mm (4.036 sq. in) smaller in area.
It's about nine-and-a-half times as heavy as a Grain of Rice
In other words, 3 grains is 9.3 times the weight of a Grain of Rice, and the weight of a Grain of Rice is 0.11 times that amount.(conventional; US; long-, medium-, and short-gran varieties; uncooked)
With great differences in variety, the average among a sampling of common short-, medium- and long-grain rices finds that a single grain weighs about 0.320 grains before cooking. A staple through most of human history, archaeological evidence indicates that the earliest rice cultivation was about 11,500 years ago.
It's about one-fifteenth as heavy as a Penny
In other words, 3 grains is 0.08 times the weight of a Penny, and the weight of a Penny is 13 times that amount.(United States) (formally one-cent coin) (Union shield design, 2010-present)
The weight of a United States penny is 39 grains. According to a 2010 report by the United States Mint, the cost of manufacturing and distributing a penny is $0.0179 — more than its face-value.