This plant grows only in the Southwest, so I’ll give you a few hints.
When the seed is on the plant it is covered. I have opened the covering here.
The seeds are large, about the size of an almond. They are not edible but the plant is useful and is sometimes grown as a crop.
Any guesses?
Edit: The answer is now posted.
Yes, the mystery seeds from last week were from the strawberry plant, genus Fragaria.
We see the seeds (technically achenes) all the time, because the plant displays them proudly on the outside of the fruit. But how much have you thought about strawberry seeds?
For example, can you plant strawberry seeds and grow a new strawberry plant?
You have probably seen strawberry plants at the nursery. You might even have grown them yourself.
Although those starter plants are convenient and speed up the arrival of an edible crop, the answer is that you can grow strawberries from seeds.
Our garden strawberries are the result of a cross between two different species of strawberries. Varieties have been developed from those original crosses. Some varieties will grow true to their parents, and others will be a new mix. If you want to be sure to grow reliable strawberries, you can get packets of strawberry seeds from a nursery or online.
But what fun is that? 
Being scientists to the core, we want to find out for ourselves. We have taken some fresh strawberries from the grocery store, blended them in the blender for a few seconds and then spread them on some moist potting mix. We covered the seeds lightly with soil, and will let you know our results.
One question you may have is whether the seeds need a cold period, like apples do. That is one variable we need to examine. One scientific paper I examined suggested that the seeds do not necessarily need a cold treatment.
Source: An improved technique for the germination of strawberry seeds
Have you ever grown strawberries? (I know someone who left a comment on the mystery seed post grew them commercially). How about from seed? If you give it a try, be sure to let us know what happens.
Have you heard of “smart materials?” After reading about them in Chemistry: Getting a Big Reaction by Simon Basher and Dan Green (see review at Wrapped in Foil), I had to find out more. 
The term “smart materials” seems rather vague, but in chemistry and physics it has a distinct meaning. Smart materials are a relatively newly-discovered (mostly in the last 30 years) set of substances that are getting a lot of attention because of their astonishing abilities to react to the environment.
Smart materials may react to changes in:
in amazing ways.
Examples:
1. Shape-memory alloys are mixes of metals with the ability to be bent and stretched out of shape and then return to a coil when heated.
This Steve Spangle video shows an example of a nickel-titanium alloy:
Does anyone know where you can buy some of this?
Steve Spangler has a memory metal experiment, but I couldn’t find it listed as a product.
2. Shape-memory polymers are plastics that also change shape when exposed to heated water.
Check out this sample from… well, you will know where it is from if you watch the video.
3. Thermochromic paint contains pigments that change color at different temperatures.
You can sometimes find plastic toys that are meant to be put into the bathtub. If the water is too hot, the toys will let you know because they change color. In the future your walls may change color throughout the day with changes in temperature.
4. Photochromic paint or pigments change color at different light levels.
In this video you will see some beads that indicate whether you are being exposed to UV light or not.
Activity suggestions and more information about Solar -UV Beads and how they work.
You can find Solar or UV-sensitive beads from a number of different retailers, including Amazon (Please see disclosure page for information about my affiliation with Amazon).
5. Electrochromic materials in LCD’s that are voltage sensitive and change the color of the screen.
Smart materials are already being used in eyeglass frames that return to shape after being smashed, and in certain dental appliances. Can you imagine such futuristic applications as repairing dents in your fender by applying heat? How about taking wrinkles out of clothes with the warmth of a hair dryer, as seen in this video?
Aren’t smart materials extremely cool? If you have any sources of smart materials and/or activity ideas to share, please let me know.